With the new airport rail link plus a slew of other transport options, it's quick and easy to get from the airport into the city even if you are traveling during rush hour. If you are, consider taking the rail link, taxi, or bus to a convenient Subway or Skytrain station for the rest of the journey.
Airport Rail Link
The Airport Rail Link is the cheapest and fastest way out of the airport and into downtown Bangkok. When you arrive, follow the signs for the train station, which is located on the basement floor. The express train will take you directly to Makkasan Station in about 15 minutes. From there you can connect to the local line and take it two stops to Phayathai Station, where you can connect to the Skytrain.
Metered taxis are the easiest way to get out of the airport and to your hotel. Once you clear customs and immigration, head downstairs to the first level, there will be a taxi line outside. The fastest way to get into the city is on the expressway and tolls will cost you an additional 70 baht or more depending on where you are going. Most taxi drivers are honest but some will try to offer you a flat rate to take you to your hotel. Insist on the meter.
Airport limos cost about 3 times the price of a taxi but are very comfortable and drivers almost always speak enough English to get you where you need to go with no confusion. If you have a lot of people or stuff, you can also get an airport limo minibus. If you opt to go that route, there are airport limo desks inside the baggage claim area and once you clear customs and immigration.
Express Airport Buses
There are express buses running from the airport on four different routes into central Bangkok including Silom Road, Khao San Road and the Sukhumvit Area. Buses run from 4 am to 11 pm and you can get tickets at the airport bus counter on level one of the airport.
Public buses run 24 hours a day from the airport and cost 35 baht per trip. To catch one, take the shuttle from the terminal to the transportation center. There are 12 different routes from Suvarnabhumi Airport to various parts of greater Bangkok. There's also a government bus that will take you straight from the airport to Pattaya.