Taxis to Suvarnabhumi can be hailed on the street or arranged by your hotel. Avoid taxis that park outside your hotel. There is no 50-baht surcharge added to the fare but the passenger must pay any tollway fares. Make sure the taxi driver turns the meter on. The rough cost of a taxi from central Bangkok is normally around 250 – 350 baht including tollway. The Journey should take about 30 – 60 minutes from central Bangkok.
The airport link train departs from Phaya Thai station connected to a BTS station of the same name. Service hours are 06.00am – 24.00. Trains leave every 15 minutes and take 30 minutes to arrive at the airport terminal station in the basement of the passenger terminal. The fare is 45 baht. The train picks up at 2 more locations in central Bangkok at Ratchaparop and Makkasan stations. Makkasan station links to the MRT Phetchaburi station by a walkway. Ratchaparop station is within walking range of hotels in the Pratunam district.
There are hourly departures from Khaosan Road. Bookings can be made at your guest house or at travel agents. They will usually pick you up at your guest house. Tickets are around 150 baht. Book in advance to make sure of a seat.
There is an Airport Bus (S1) which runs from Sanam Luang, departing from near the WWI monument. The bus then runs up Ratchadamnoen Road picking up at the bus stops near the Burger King end of Khao San Road, Democracy Monument and the Kok Wua intersection. Departures are every 30 minutes between 06.00 and 20.30. The fare is 60 baht.
There are 24-hour city bus services to Suvarnabhumi. Bus/van 551 runs from Victory Monument, bus/van 552 runs from BTS On Nut station, bus 554 from Don Mueang Airport, bus 556 from the Southern Bus Terminal. The fare is 35 baht and the route is mostly on the expressway. Not recommended if you have a lot of luggage.
If you have an early flight you might want to consider staying at the airport. The nearest and best hotel is the Novotel which connects to the airport by a walkway or shuttle bus. There are also other hotels and hostels nearby.