Sukhumvit – The long Sukhumvit Road, changing name to Ploenchit Road and Rama I Road going west, is Bangkok's modern commercial core, full of glitzy malls and hotels. The Skytrain intersection at Siam Square is the closest thing Bangkok has to a centre.
Silom – To the south of Sukhumvit, the area around Silom Road and Sathorn Road is Thailand's sober financial center by day, but Bangkok's primary party district by night when quarters like the infamous Patpong come alive.Suriwongse Road -The Entrance to Patpong road and the gay paradise opposite to it.
Rattanakosin – Between the river and Sukhumvit lies the densely packed "Old Bangkok", home to Bangkok's best-known wats. Yaowarat (Chinatown) and sights around the Chao Phraya River are also included here. Bangkok's backpacker mecca Khao San Road and the surrounding district of Banglamphu are located on the northern part of Rattanakosin.
Thonburi – The quieter west bank of the Chao Phraya River, with many small canals and some offbeat attractions.
Phahonyothin – The area around Phahonyothin Road and Viphavadi Rangsit Road is best known for the Chatuchak Weekend Market and Don Muang Airport.
Ratchadaphisek – The district north of Sukhumvit centered around Ratchadaphisek Road (part of which is called Asoke) and reaching from Phetchaburi Road to Lat Phrao. This area has really opened up recently as the new metro line follows Ratchadaphisek Road.
The concrete jungle of central Bangkok
Just under 14 degrees North of the Equator, Bangkok is a tropical metropolis that is also one of the most traveller-friendly cities in Asia. A furious assault on the senses, the first things that impress many visitors are the heat, the congestion both on streets and sidewalks, the pollution inherent to rapid development, the squalor that accompanies a gaping chasm between rich and poor, and the irrepressible smiles of the Thais. Despite the sensationalized international news reports and first impressions, the city is surprisingly safe, more organized than it initially appears, and full of hidden gems waiting to be discovered. The high relative humidity and warm temperature favor the growth of tropical plants — you'll find exotic orchids and delicious fruit everywhere. Thai cuisine is singular, justifiably famous, varied, and affordable. Bangkok, for many, represents the quintessential Asian capital. Saffron-robed monks, garish neon signs, graceful Thai architecture, spicy dishes, colourful markets, traffic jams, and the tropical climate come together in a happy coincidence. It is difficult to leave with lukewarm impressions of the city.
Bangkok (originally Bang Makok) was a small village on the banks of the Chao Phraya river, until a new capital was founded on the west bank (present-day Thonburi) after the fall of Ayutthaya. In 1782, King Rama I built a palace on the east bank (now Rattanakosin) and renamed the city as Krung Thep, as it is now known to Thais -- the City of Angels (and much more: the full name is listed as the world's longest place name by the Guinness Book of Records; an English rendering goes like this: "Krung thep mahanakhon amorn ratanakosin mahintharayutthaya mahadilok pop noparatratchathani burirom udomratchanivetmahasathan amornpiman avatarnsathit sakkathattiyavisnukarmprasit" -- "The city of angels, the great city, the residence of the Emerald Buddha, the impregnable city (of Ayutthaya) of God Indra, the grand capital of the world endowed with nine precious gems, the happy city, abounding in an enormous Royal Palace that resembles the heavenly abode where reigns the reincarnated god, a city given by Indra and built by Vishnukarn"). The original village has long since ceased to exist, but for some reason foreigners never caught on to the change.
 Addresses & Navigation
Addresses in Bangkok use the Thai addressing system, which may be a little confusing to the uninitiated. Large roads such as Silom or Sukhumvit are thanon (ถนน), often abbreviated Th or glossed "Road/Avenue", while the side streets branching off from them are called soi (ซอย). Sois are numbered, with even numbers on one side and odd ones on the other. Thus, an address like "25 Soi Sukhumvit 3" means the 25th building on the 3rd soi of Sukhumvit Road. While the soi numbers on each side will always advance upward, the numbers often do not advance evenly between sides - for example, Soi 55 could be across from soi 36. Many well-known sois have an additional name, which can be used instead of the number. Soi 3 is also known as "Soi Nana", so the address above might thus also be expressed as "25 Soi Nana". The extension /x is used for new streets created between existing streets, as seen in Sukhumvit's soi pattern 7, 7/1, 7/2, 9, 11. Note that some short alleys are called trok (ตรอก) instead of soi.
To make things a little more complex, some large sois like Soi Ekamai (Sukhumvit Soi 63) and Soi Ari (Phahonyothin Soi 7) have their own sois. In these cases an address like "Soi Ari 3" means "the 3rd soi off Soi Ari", and you may even spot addresses like "68/2 Soi Ekamai 4, 63 Sukhumvit Road", meaning "2nd house beside house 68, 4th soi off Ekamai, the 63rd soi of Sukhumvit". In many sois the house numbers are not simply increasing, but may spread around.
To further bewilder the tourist who doesn't read Thai, the renderings of Thai street names in the Latin alphabet are not consistent. The road running towards the (former) airport from the Victory Monument may be spelled Phahon Yothin or Pahon Yothin or Phahonyothin or Phaholyothin depending on which street sign or map you consult. It's all the same in Thai, of course -- only the romanisation varies.
And if that's not confusing enough, most of the larger streets tend to change names altogether every few kilometers. Sukhumvit is called Sukhumvit on one side of the tollway (roughly east), but it becomes Ploenchit just before you cross Thanon Witthayu (aka Wireless) going towards the river. Keep going just a few more streets and it becomes Thanon Rama I (usually said as just Rama I) after you pass Thanon Ratchadamri. But if you were to turn right onto Ratchadamri, in just a few blocks you'll find yourself on Thanon Ratchaprarop (past Petchaburi, aka New Phetburi, which is called Phitsanulok closer to the river). Got it?
But wait, there's logic to these name changes: most of them are neighborhoods. It wouldn't make sense to call the road Sukhumvit if it's no longer running through the Sukhumvit area, would it? Thus, Sukhumvit becomes Ploenchit where it runs though the Ploenchit area. It's when you're able to grasp the city in terms of its neighborhoods that it both becomes more navigable and more charming. Likewise, Pratunam and Chatuchak are much more than just markets; they're boroughs, each with its own distinct character.
Related to this last point, compass directions are not widely used by Thais to navigate in Bangkok. That's probably because they aren't very useful: the city's darwinistic layout, the changing street names, the winding river, and the lack of obvious landmarks all conspire to confuse your internal compass. Thus, asking for directions in terms of "is that west from here?" will probably earn you little more than a confused look from a local. You're better off to familiarize yourself with the neighborhoods and navigate to and from them. "How do I get to Thonglor?" will get you there faster than asking for directions to Sukhumvit Soi 55.
One exception: the Chao Phyra River is THE landmark in Bangkok, and many directional references can be made as "toward the river" or "away from the river". If you aren't TOO close, that is: since the river winds around the most popular tourist areas, river references tend to be most helpful when you're wandering farther afield than Banglamphoo or Sanam Luang or Rattana. And wander you should.
 Get in
 By plane
Bangkok now has two airports operating. Allow at least three hours to connect between them.
 Suvarnabhumi Airport
Bangkok used to have a departure tax (called the "Passenger Service Charge") of 700 baht for international flights. This was payable in cash after check-in; however, it is now included in your airline ticket. If you purchased the tickets prior to Dec 2006, this may not be the case. Check your tickets!
Located 30 kilometres (19 miles) to the east of Bangkok, space-age Suvarnabhumi Airport (สุวรรณภูมิ, pronounced "soo-wanna-poom", (IATA: BKK) (ICAO: VTBS),  started operations in September 2006 and is now Bangkok's main airport, used by all international flights as well as all Air Asia and some Thai Airways domestic flights. There is only one terminal building, which covers both domestic and international flights, but it's huge (by some measures the world's largest) so allow time for getting around.
All the facilities you'd expect are available (transit hotel, ATMs, money exchange). The cheapest place to eat is the Magic food court on the 1st floor, while perhaps the most comfortable and relaxing of the airport's restaurants and cafes is the Sky Lounge on the 5th floor. Here you can have your latte while sitting in plush leather sofas and enjoying a panoramic view over the runways - prices are also quite reasonable with coffee around 70 baht a cup. There are a few stores in the check-in area including a convenience store and a post office; however, the real shopping experience awaits travellers on the other side of immigration in the departure lounge area where the number of shops and duty free outlets leaves you wondering if you are in a mall or an airport. Beware, though, that past security in the gate waiting area there is practically nothing except steel chairs.
Limousine taxis (which charge by distance, e.g. around 800 baht to central Sukhumvit) can be reserved at the limousine hire counter on the 2nd floor (just outside Arrivals), and a limited number of ordinary metered taxis are available outside the exit on the 1st floor (take the escalator downstairs). If there is a huge taxi queue, consider taking a free shuttle bus to the satellite terminal, which has more taxis. There is a 50 baht surcharge on the meter, meaning that trips to the city will cost 300-400 baht (plus 65 baht highway tolls) and take 40-60 minutes depending on traffic.
There is also a stop outside the 1st floor exit for airport express buses , which charge a flat 150 baht and operate hourly until midnight, covering four routes, each taking about 60 to 90 minutes:
AE2: Suvarnabhumi-Khao San Road
AE4: Suvarnahhumi-Victory Monument-Hua Lamphong (train station)
Local (Bangkok) public buses to/from Suvarnabhumi charge a flat 35 baht. To take a public bus, you must first take a free shuttle bus ride (from the outside 2nd floor) to the separate terminal. The lines are:
550: Suvarnabhumi-Happy Land
551: Suvarnabhumi-Victory Monument (BTS)
552: Suvarnabhumi-On Nut (BTS)-Klong Toei
552A: Suvarnabhumi - Sam Rong
553: Suvarnabhumi-Samut Phrakan
554: Suvarnabhumi-Don Muang Airport
555: Suvarnabhumi-Rangsit (Expressway)
557: merged with 558
558: Suvarnabhumi-Central Rama II-Wong Wien Yai
559: Suvarnabhumi-Rangsit (Outer Ring Road)
These services take about 1 hour to 2 hours depending on Bangkok traffic and frequency is usually every 20 mins during daytime and night time ranges from 20 mins to 1 hour depending on route. Long-distance 1st class bus services connect Suvarnabhumi directly with Chachoengsao, Hua Hin, Nong Khai, Pattaya, Rayong, and Trat.
An airport express train to the future City Air Terminal at Makkasan (connecting to MRT Phetchaburi) and onward to Phaya Thai (connecting to BTS Phaya Thai) is under construction, but is not expected to be ready before the end of 2007 at the earliest. Die-hard rail fans with lots of time to kill can take bus 517 to Hua Takhe station (15 baht), a few km from the airport, and continue on any 3rd class train to Asok or Hualamphong (7 baht).
At present, there are only a few hotels located near Suvarnabhumi Airport, though with huge construction projects planned for the area this will change over the next few years. Day room facilities for transit passengers are now available at the 'Miracle Grand Louis Tavern' on floor 4, section G (Tel+66 6 317-2211, 2000 baht per 4-hour block, no reservations accepted). Cheapskate travelers looking for a free quiet place to doze undisturbed at night should head for the prayer rooms.
The Tourist Authority of Thailand and other hotel and tourist agencies have counters on the second floor of the main terminal. These agencies offer hotel reservation service. Check for special promotions and also whether the hotel offers airport pick up and drop off service - especially useful for late night arrivals and early morning departures.
Novotel Suvarnabhumi Airport Hotel, Suvarnabhumi Airport. Tel:+66 2 131-1111 firstname.lastname@example.org . The only hotel in the airport itself, connected to the main airport terminal by a pedestrian bridge. (As of Mar 2007, the pedestrian bridge is still not ready for use and passengers are taken to the hotel via a free shuttle bus service which takes less than 5 mins.) Rooms: 3,500+ baht.
Queen's Garden Resort, 44 Soi 7, Suvarnabhumi, Lat Krabang. Tel:+66 2734 4540-3. Fax: +66 2 734 4542, e-mail email@example.com, . The hotel is just 5-10 minutes from Suvarnabhumi Airport. Located on the banks of a sleepy river, the Resort has views towards Lat Krabang Temple. Rooms 900+ Baht.
Royal Princess Srinakarin, 905 Moo 6, Srinakarin Road, Nongbon, Pravet. Tel:+66 2 728-400. Fax:721- 8432 - a 20-30 minute drive from airport. Rooms 3,500+ baht.
Sananwan Palace, 18/11 moo 11. Sukapibarn Road 5 , Bangpli Yai. Tel:+66 2 752-1658 ,(Mobile) +66 818644615. Family-owned budget accommodation with swimming pool, TV and high speed internet about 20 minutes drive from the airport. Rooms with A/C: 600 baht.
Grand Inn Come Hotel, 99 Moo 6, Kingkaew Road, Rachataeva, Bangplee, Samutprakan. Tel:+66 2 738 8191-3 - about a 15-20 minute drive from the airport. Bus 553 stops here. Rooms between 1,200 - 2,000 baht.
Avana Hotel, 23/1 Moo 12 Soi 14/1, Bangna-Trad Road. Tel:+66 2 763-2900. 3-star hotel about 30 minutes drive from the airport. Rooms 1,200 to 3,000 baht.
Nasa Vegas Hotel. 44 Ramkhamhaeng Road. Tel :+66 2 719-9888 Fax:+66 2 719-9899 - about 15 mins drive from the new airport. Rooms from 590 + baht.
Ratchana Place. 199 Moo 4, Soi Wat Sirisaothong, Bangna Trad Highway KM 26, Bangbo, Samutprakan 10540 Tel:+66 2 313-4480~9 firstname.lastname@example.org - about 15-20 mins drive from the airport. Rooms between 350 - 700 baht.
Bansabai Hostel. 8/137 Moo 3, Soi Sahakon 15, Latphrao 71, Latphrao Rd, Bangkok 10230, Thailand+66 2 932-9200  - about 30-40 mins drive from the airport. Rooms rate between 600 - 800 baht.
Unico Grande Sukhumvit. 27 Sukhumvit Soi1, Sukhumvit Rd, Klongtoey-Nua, Wattana Bangkok 10110, Thailand+66 2 655 3993  - about 30-40 mins drive from the airport. Rooms rate between 2,500 - 5,000 baht.
 Don Muang Airport
Don Muang Airport (IATA: DMK) (or Don Mueang), 20 km north of downtown, was Bangkok's main airport until 2006. The airport handles Nok Air, PB Air and most Thai Airways domestic flights, but the former international terminal is now limited to charters and general aviation.
The public taxi stand is located on the sidewalk outside the arrivals area (don't be fooled by all the taxi service booths in the main hall), and is probably your best bet for getting into town — it's also your only option after 11 PM. Give your destination (English is understood) and you will receive a two-part ticket at the booth. The charge into town will be the meter + 50 baht + toll if you take the expressway (recommended, 30-70 baht), for a usual total of 200-300 baht. The small part is for your driver, the large part is for you. This ticket is for complaints and is how the system is enforced: hold on to it to help avoid arguments later. The trip into town takes 30 minutes and up depending on traffic conditions.
If the line at the taxi stand is long or you need a more spacious car, you may want to book a (so-called) limousine from the desks in the terminal. This will get you a slightly nicer car at about twice the price (500-600 baht). Ignore any touts outside and do not get into any car with white license plates, as these are not licensed to carry passengers.
Across a covered overpass from the airport is the train station. Tickets to Hualamphong station cost 5 baht at the ticket booth. While taking the train is the cheapest way to get from the airport to Bangkok, it is not for the faint-of-heart: schedules are erratic, the run-down passenger cars often have beggars roaming through them, and are relatively empty late at night.
There are also a number of public transport buses going by the airport. Just take a overpass to the real road bypassing the airport and stop the bus of your choice. For example the air-con bus 504 will take you to the World Trade Center, from where you'll have access to the Skytrain as well as many other buses, or Lumpini Park, from where you get access to the subway, for 20 Baht. Note that large baggage is not allowed.
If you're flying Thai Airways, you can do a city check-in at Lad Phrao MRT station, from where free shuttle buses leave 1:50 before each Thai flight. The same buses also run in the reverse direction from the airport.
 By bus
Bangkok's three official long haul bus terminals are:
Eastern Bus Terminal - also known as Ekamai, this relatively compact terminal is located right next to Ekamai BTS station on Sukhumvit (E7). Ekamai serves Eastern Thailand destinations, including Pattaya, Rayong, Ban Phe, Chanthaburi and Trat.
North & North Eastern Bus Terminal - also known as Moh Chit (or Mor Chit or Morchit), this is the largest, busiest, and most modern terminal. The upper floor serves the North-East (Isaan); the ground floor serves the North, as well as sharing some destinations with Ekamai (including Pattaya, Rayong, Chanthaburi and Trat). It's a 30-baht moto hop (or a lengthy hike across Chatuchak Park) from BTS Moh Chit/Metro Chatuchak stations (N8/18), or take the 77 bus and pay the 7-baht flat fare on board.
See the Phahonyothin District guide for more details.
Southern Bus Terminal - also known as Sai Tai Mai, this older and relatively chaotic sprawling terminal serves all points west and south from its somewhat inconvenient location on the "wrong" side of the river. The terminal is scheduled to move to a new, even more remote location in Phutthamonthon Sai 1 in December 2007 — enquire locally.
See the Thonburi District guide for more details.
when arriving in Bangkok...
...late at night, the easiest way from Northern or Southern terminal to your final destination will be by meter taxi.
...by tourist bus you may find yourself delivered to their favorite hotel or guest-house, otherwise you'll probably be dropped off in the vicinity of one of the long haul terminals, or if it's a service catering primarily for backpackers, somewhere near Khao San Road.
 By train
The three main stations in Bangkok are:
 Hualamphong Train Station
Inside view of Hualampong train station, looking towards the platform
The main station and the terminus of the Bangkok Metro line. Located right in the middle of downtown Bangkok, it is a huge and surprisingly nice station, built during the reign of King Rama VI and spared bombing in world War II at the request of the Free Thai underground. The station has a good tourist office. (Only listen to the people at the Info desk - anyone walking around offering to help you 'find' a hotel or taxi is just a tout, even if they are wearing very official looking badges).
Tickets for trains leaving the same or next day can be bought on the counters under the red/orange/green screens (see photo). The Advance Booking Office is located to the right of the platforms as you walk towards them and is quite well organised. You can select your seat/berth from a plan of the train, and payments by credit card are accepted.
The taxi pick up and drop off point is to the left of the platforms as you walk towards them, and is generally chaotic at busy periods with scant regard for any queue.
The left luggage facility is at the opposite end of the concourse, on the far right as you walk away from the platforms.
WARNING: The TAT Authorized Tourism Information offices in the second floor sell you a private "VIP bus" ticket if there is no place in first and second class trains. They offer a direct trip to the destination with a VIP bus faster than the train. Although the trip starts with a VIP bus, it ends up with a "surprise" transfer to a minibus and extremely long journeys. Just refuse the offered private bus ticket and buy public bus tickets from the main bus terminals if you cannot find ticket for train.
 Bang Sue Train Station
If coming from the north or north-east, connecting to the Metro here can shave the last half-hour off your train trip. This is not a very good place to board trains though, as there is practically no information or signage in English. However, this situation will doubtless improve as more and more long-distance departures are switched to here from Hualamphong.
See Phahonyothin District for more details.
 Thonburi Train Station
Also known as Bangkok Noi, this station is located on the "wrong" side of the river in Thonburi District and is the starting point for services to Kanchanaburi (via Nakhon Pathom), River Kwai Bridge and Nam Tok.
There are two daily 3rd class trains: 
depart Thonburi 07:45, arrive Nam Tok 12:20, return 13:00, terminate Thonburi at 17:36
depart Nam Tok 05:25, arrive Thonburi 10:05, return 13:50, terminate Nam Tok at 18:20
Note that the weekend-only 2nd class air-con Kanchanaburi/Nam Tok "tourist" trains depart from Hualamphong. 
 By ship
Cruise ships visiting Bangkok arrive at Laem Chabang, about 90 minutes south-east of Bangkok and about 30 minutes north of Pattaya.
A taxi service desk is available on the wharf, but charges extortionate prices - a whopping 2600 baht to charter a taxi (4 passengers), or about 5000 baht to charter a minibus (usually 11 passenger seats), for a trip into Bangkok. Slightly lower prices can be found by walking out to the main road (about 4000 baht for a minibus), however even these rates are almost double the typical rate in the opposite direction. Better deals may be possible for round trips (even if returning the following day).
Frequent first and second class bus services directly connect Laem Chabang with Ekamai (Bangkok's Eastern Bus Terminal, on Sukhumvit); less frequent direct services run to Moh Chit (Bangkok's Northern Bus Terminal). A first class air-con bus (blue and white) to either will usually take 90 minutes or less; the fare is around 100 baht. A good way to make the most of a quick visit is to board an Ekamai bus and then disembark early at the On Nut Skytrain Station on Sukhumvit Road in Bangkok (the bus will always pause here provided a passenger requests it); in the opposite direction, use the Ekamai Skytrain Station and board the bus at the terminus. To get to or return from the Chatuchak Weekend Market, use the Moh Chit bus instead.
Buses en route to Pattaya (southbound) can be boarded at the traffic lights on Sukhumvit Road in Laem Chabang, are extremely frequent (at least 10 per hour), and charge less than 50 baht.
 Get around
Bangkok has the full spectrum of public transportation methods. Buses and taxis operate everywhere in the city. The Sky Train (BTS) and metro are available only in the city centre. And vans generally operate only in more out-lying areas.
Queen Sirikit NCC
Phra Ram 9
Thai Cultural Center
 By train
The Bangkok Skytrain (BTS, pronunced bee-tee-et in Thai but also rót fai fáa or just skytrain) deserves a visit simply for the Disneyland space-ageness of it. Built in a desperate effort to ease Bangkok's insane traffic and pollution, the Skytrain covers most of downtown and is especially convenient for visiting the Siam Square area. There are two lines: the light green Sukhumvit line which travels along Sukhumvit road and then goes up Phayonyothin to northern Bangkok, where it terminates near the Chatuchak Weekend Market (N8), and the dark green Silom line, which travels from the Silom area, interchanges with the Sukhumvit line at Siam Square (C) and ends at National Stadium, right next to MBK. There isn't, unfortunately, a station near Banglampu District (aka the Khao San Road area), but the river ferry connects between Tha Banglampu and Tha Sathorn, which is under the Silom line terminus at Saphan Taksin (S6).
You must have 5 or 10 baht coins to purchase Skytrain tickets from the vending machines near the entrance, so hold on to them. Fares range from 15 to 40 baht depending upon how many zones you are travelling. Consult the map (in English) near each ticket machine. If you do not have coins, queue for change from the staff at the booth. If you are in town for several days, weigh your options and consider a rechargable stored-value card (from 100 baht, with a 30-baht refundable deposit), a "ride all you like" tourist pass (from 100 baht/day) or a multiple ride pass of 10 trips or more. They will certainly save you time, scrambling for coins, and maybe even money. Check for information with the English speaking staff.
Four stations are fully accessible to wheelchair users, plus one station, On Nut is accessible only on the arrival side. The other fully accessible stations are Asok/Sukhumvit, Siam, Chong Nonsi and Mo Chit. To acceed to concourse level in these stations, you can use the lift - press the call button and an attendant will come and get you. At On Nut stations on the departures side, the attendant will help you also to get to platform level through the escalator since the elevator can be used only to get to intercourse level. Siam Station is also accessible independently through the linked Siam Paragon department store.
Bangkok Metro finally opened in July 2004. The Blue Line connects the central Hualamphong railway station (1) to the northern Bang Sue station (18), with interchanges to the Skytrain at Silom/Sala Daeng (3/S2), Sukhumvit/Asok (7/E4) and Chatuchak/Mo Chit (15/N8). You can also transfer to north/northeast-bound SRT trains at the northern terminus Bang Sue.
Metro tickets are not interchangeable with Skytrain tickets. Rides cost from 15 to 39 baht depending on distance; pre-paid cards of up to 1000 baht are also available. For single ride fares, a round plastic token is used.
The subway stop for the Chatuchak Weekend Market is not Chatuchak Park, but one stop further at Kamphaeng Phet (16). The latter drops you right inside the market.
All metro stations are fully accessible to wheelchair users. If the elevator has been put out of service, just ask the security staff present at every station and an attendant will come and get you to help you to deal with all the process of buying tickets and get to the train platform level.
 By boat
Chao Phraya Express Boat
A ride on the Chao Phraya River should be high on any tourist's agenda. The cheapest and most popular option is the Chao Phraya Express Boat, basically an aquatic bus plying up and down the river. The basic service plies from Wat Rajsingkorn (S4) all the way to Nonthaburi (N30) is now 13 baht, with stops at most of Rattanakosin's major attractions including the Grand Palace, the Temple of Dawn, etc. Board at piers with a sign showing the route and pay the ticket collector who will approach you bearing a long metal cylinder. In addition to the basic service, there are express services flagged with yellow or orange flags, which stop only at major piers and should be avoided unless you're sure where you're going. The new signposting of the piers is quite clear, with numbered piers and English route maps, and the Central station offers easy interchange to the BTS Saphan Taksin station.
In addition to the workaday express boat, there is also a Tourist Boat which stops at a different subset of piers, offers commentary in English and charges twice the price. The boats are slightly more comfortable and not a bad option for a hop or two, but don't get bullied into buying the overpriced day pass.
Canal boats also serve some of Bangkok's many canals (khlong). They're cheap and immune to Bangkok's notorious traffic jams, but mostly used by locals who use these water taxis to commute to work and school and shopping, so you get to see the 'backside' of the neighborhoods, so to speak. They're also comparatively safe -- just watch your step when boarding and disembarking (they don't stop at the pier for long) and be wary of the water as it can be quite polluted, do not let it get in your eyes. Pay the fare (8-20 baht) to the crazy helmet-wearing ticket collectors who hang onto the outside of the boat, ducking at bridges, as it barrels down the canal. One particularly useful line runs up and down Khlong Saen Saep, parallel to Petchaburi Road, and provides the easiest access from the city center to the Golden Mount. There's a boarding pier across from the WTC under the bridge where Ratchadamri crosses the khlong near Petchburi, and piers now even have (tiny) signs in English.
Finally, for trips outside the set routes, you can hire a long-tail river taxi at any major pier. These are fairly expensive and will attempt to charge as much as 500 baht/hour, but with haggling may be suitable for small groups. To circumvent the mafia-like touts who attempt to get a (large) cut for every ride, agree for the price of the shortest possible ride (half an hour etc), then negotiate directly with the captain when on board.
 By bus
Local buses, mostly operated by the Bangkok Mass Transit Authority (BMTA), are cheapest but also the most challenging way of getting around, as there is a bewildering plethora of routes, usually marked only in Thai. If you can speak Thai you can call 184 Bus Route Hotline. Bus stops usually list only the bus numbers that stop there and nothing more. They are also subject to Bangkok's notorious traffic, often terribly crowded, and many are not air-conditioned. Honestly, unless you're terribly strapped for cash, or are staying in Bangkok for a while, it is not worth figuring out the buses! Take a taxi. The hierarchy of Bangkok's buses from cheapest to best can be ranked as follows:
Small green bus, 7.50 baht flat fare. Cramped, no air-con, no fan, famously suicidal drivers, not advisable for more than short hops.
Red bus, 7 baht flat fare. More spacious and fan-cooled (in theory). Unlike other buses, some of these run through the night (1.50 baht surcharge). These buses are BMTA run.
White/blue bus, 8 baht flat fare. Exactly the same as the red buses, but cost one baht more. These buses are owned by private entities operated in conjunction with BMTA.
Blue/Yellow and Cream/Blue air-con, 11 baht for the first 8 kilometers, up to 18 baht max. These buses are quite comfy. The blue/yellow striped buses are privately owned while the Blue/Cream buses are BMTA owned.
Orange air-con (Euro II), 13 baht for the first few kilometers, up to 22 baht max. These are all BMTA-run, newer, and more comfortable.
Purple Microbus, 20 baht flat fare. Skytrain feeder services used to use these, but the service has been terminated.
Buses stop only when needed, so wave them down (arm out, palm down) when you see one barreling your way. In all buses except the Microbus, pay the roaming collector after you board; on Microbuses, drop the money into a slot next to the driver as you board. In all buses, keep the ticket as there are occasional spot-checks, and press the signal buzzer (usually near the door) when you want to get off.
Two further pitfalls are that buses of the same number may run slightly different routes depending on the color, and there are also express services (mostly indicated by yellow signs) that skip some stops and may take the expressway (2 baht extra).
The best online resources for decrypting bus routes are the official BMTA homepage, which has up-to-date if slightly incomplete listings of bus routes in English but no maps, and the ThailandOnline bus route map (bus info only in Thai, the map itself is bilingual). As a printed reference, the Bus Routes & Map guide (50 baht) by Bangkok Guides is another option.
Recently they have changed the rules regarding luggage on local buses within Bangkok, with the exception of airport buses you cannot take large amounts of luggage (ie. backpacks or suitcases) on the local buses.
Useful bus lines include the following:
Red Bus No. 2 can bring people from Sanam Luang (very close to Khao San Road) to Sukhumvit Road. It's a good way to get from the Khao San Road area to connections with the Skytrain or MRT. It passes Pantip Plaza on the way.
'Air Con Bus 511 takes people from Sukhumvit and the Democracy Monument to the Southern Bus Terminal. If you want to go to Sukhumvit from Khao San Road, be sure to take the bus WITHOUT the yellow sign in front, as this will take you to Rangsit.
Red Bus No. 15 will take you from Khao San Road to Siam Square.
 By taxi
Taxis are a quick and comfortable way to get around town, at least if the traffic is flowing your way. All taxis are now metered and air-conditioned: the hailing fee is 35 baht and most trips within Bangkok cost less than 100 baht. There are no surcharges (except from the airport), even at night. A red lit sign on the front window means that the taxi is available.
When the meter is switched on you will see a red '35' somewhere on the dashboard or between the driver and you. Be sure to check for this at the start of the ride, as many drivers will "forget" to start the meter in order to overcharge you at the end of your trip. Most will start the meter when asked politely to do so (meter na khrap (male) / kha (female)); if the driver refuses to use the meter after a couple of attempts, simply exit the taxi. In some cases, late at night and especially near major tourist districts like Khao San or Patpong, you will need to walk a block away to catch a meter cab. The effort can save you as much as 150 baht. This is often also the case for taxis that park all day in front of your hotel. The only two reasons that they are there: 1) To take you places where they can get their commissions (Jewelry stores, massage parlors, etc) and 2) To overcharge you by not using the meter. Your best bet is to walk to the road and catch an unoccupied metered taxi in motion (easier than it sounds, as Bangkok traffic tends to crawl the majority of the time, and one car out of four is a taxi). Be sure to either know the correct pronunciation of your destination, or have it written in Thai; taxi drivers in Bangkok are notoriously bad at reading maps. Most hotels and guesthouses will happily write out addresses in Thai for you. While most drivers will recognize the names of tourist hot spots, even if grossly mispronounced, it is often difficult to properly pronounce addresses in Thai, a tonal language. If your mobile phone works in Thailand, it is sometimes useful to phone your hotel and ask the staff to speak to your driver in Thai.
If you're pinching pennies or fussy about your means of transportation, you may wish to think twice before getting into one of the (very common) yellow-green taxis. They are owner-operated and of highly variable quality, and occasionally they have rigged meters. All other colors belong to large taxi companies, which usually enforce their standards better.
From the airport and on some routes in the city the driver will ask if he should use the Tollway. You should affirm this, it will save a lot of time. You have to pay the cost (20/40 baht) immediately. Watch how much the driver really pays, they may try to keep the change.
When getting out, try to have small bills (100 baht or less) or expect problems with change. Tips are not necessary, but are certainly welcome (especially considering that taxi fares have not risen in well over 5 years, despite rising gas prices!). Note that most local passengers will round up, or leave any coin change as tip.
 By motorbike
When traffic slows to a crawl and there are no mass-transit alternatives for your destination, by far the fastest mode of transport is a motorbike taxi (or in Thai, "motosai lapjang"). No, those guys in the pink smocks aren't biker gangs; they're motosai cabbies. They typically wear colorful fluorescent yellow-orange vests and wait for passengers at street corners and near shopping malls. Prices are negotiable; negotiate before you ride.
WARNING: Motorcycle accidents are brutally common, and many (tourists and Thai alike) consider transportation of this sort to be inherently hazardous. Motorcycle taxis in Bangkok should generally be avoided except as a last resort.
For the unfaint-of-heart, a wild motosai ride can provide a fantastic rush. Imagine weaving through rows of stopped vehicles at 50km/h with mere centimetres to spare on each side, dodging pedestrians, other motorbikes, tuk-tuks, stray dogs and the occasional elephant while the driver blithely ignores all traffic laws and defies even some laws of physics. Now, do the same ride while facing backwards on the bike and balancing a large television on your lap — then you can qualify as a local.
The overwhelming majority of motorcycle taxis do not travel long distances, but simply shuttle up and down long sois (side-streets) not serviced by other transport for a fixed 5-20 baht fare. These are marginally less dangerous, especially if you happen to travel with the flow on a one-way street.
The law requires that both driver and passenger must wear a helmet. It is the driver's responsibility to provide you with one, so if you are stopped by police, any fine is also the driver's responsibility. This is worth bearing in mind when you hire a motorbike or moped. Make sure that if there are two of you, the hirer provides two helmets not one. When riding, keep a firm grasp on the seat handle and watch out for your knees.
 By tuk-tuk
Tuk-tuks on the prowl
Finally, what would Bangkok be without the much-loathed and much-loved tuk-tuks? You'll know them when you hear them, and you'll hate them when you smell them — these three-wheeled contraptions blaze around Bangkok leaving a black cloud of smog in their wake. For anything more than a 5-10 minute jaunt or just the experience, they really are not worth the price — and, if you let them get away with it, the price will usually be 4 or 5 times what it should be anyway (which, for Thais, is around 30% less than the equivalent metered taxi fare). On the other hand, you can sometimes ride for free if you agree to visit touristy clothing or jewelry shops (which give the tuk-tuk driver gas coupons and commissions for bringing customers). The shops' salesmen are pushy, but you are free to leave after five to ten minutes of browsing. Visitors should beware though, sometimes one stop can turn in to three, and your tuk-tuk driver may not be interested in taking you where you need to go once he has his gas coupons. Also, with Bangkok's densly congested traffic it is sure to spend hours of your time.
In case you actually want to get somewhere, and you're an all-male party, be careful with the tuk-tuk drivers, they will usually just ignore your destination and start driving you to some bordello ("beautiful girls"). Insist continually and forcefully on going only to your destination.
There's also a less-heralded, less-colourful and less-touristy version of the tuk-tuk that usually serves the back sois in residential neighborhoods. They usually have four wheels instead of three and resemble a tiny truck / ute / lorry, and they run on petrol instead of LP. The maids and locals tend to use them to return home from market with loads of groceries, or for quick trips if they're available. Negotiate before you get in, but don't expect to go much beyond the edge of that particular neighborhood.