There are two major airports in Bangkok - Don Mueang and Suvarnabhumi. Both are extremely nice and architecturally sound. For most domestic flights, Don Mueang will be your landing strip.
But if you are coming from outside of Thailand, you will arrive at Suvarnabhumi. Both airports are located away from central Bangkok, but the city is easily accessible no matter where you land.
 

Suvarnabhumi Airport

Transportation options from Suvarnabhumi Airport makes the trip into central Bangkok fairly simple.
 

• AIRPORT RAIL LINK: The Airport Rail Link, part of the Bangkok Metro, takes you directly to the Phaya Thai BTS Station. From Phaya Thai, you can start exploring parts of Bangkok in any direction. The Airport Rail Link leaves every 15 minutes. A ride to Phaya Thai costs 45 baht and takes about 30 minutes. Follow the signs at the airport to board the Airport Rail Link.
• TAXI: You can, of course, grab a taxi directly from Suvarnabhumi to your hotel. As you make your way off the plane and out of customs, you will find customer service representatives that will help you find a taxi. Yes, there is a fee for this, and trips into Bangkok can often cost 500 to 600 baht, but hailing your own taxi at Suvarnabhumi is next to impossible.
• PUBLIC BUSES: Multiple city buses and shuttles will take you to different areas of the city. About 10 different bus lines take passengers into Bangkok, but knowing which one to board is tricky. Buses numbered 549 to 559 will take you to Victory Monument and Central Rama 2. The best way to know which bus to take is simply to ask. The price of traveling to any location should not cost more than 35 baht.

Don Mueang Airport

 Don Mueang Airport is smaller and simpler to navigate than Suvarnabhumi, but transportation choices from Don Mueang into Bangkok are limited.

• SHUTTLE A1 TO MO CHIT :

  Mo Chit BTS Station is the closest public transportation system to the airport. The A1 Shuttle is free to ride and leaves Don Mueang about every 20 minutes. You can navigate your way to your destination via the BTS once you arrive at the sky train.

• TAXI INTO TOWN :

  From Don Mueang to the center of town (Siam BTS), a taxi ride will take about 1 to 1.5 hours, depending on traffic. You will need to queue up for a taxi at the airport. There is a 50 baht surcharge for the service, plus meter charges. The taxi drivers at Don Mueang are safe and reliable. Plus, they know the city like the back of their hands. A ride into Bangkok from Don Mueang will cost about 250 to 300 baht.