As you may know, Bangkok has two airports: Suvarnabhumi Airport and Don Mueang Airport. Don Mueang was the main Bangkok International airport, but now Suvarnabhumi is the main Bangkok International Airport. Suvarnabhumi Airport is actually located in Samut Prakan Province which is about 25 kilometres from Bangkok city center. In this post, I will share you the choices to get to Bangkok downtown from Suvarnabhumi Airport. Here are the transportation modes that take you to Bangkok City Center.
Airport Limousine: This is the most expensive and convenient choice. There are various types of cars available for you to choose. From the airport to any places, the fare can cost from 800 baht up to around 3,000 baht depending on the types of cars and travel distance.
Taxi: Taxis are available at the airport. The fare depends on the travel distance and also traffic condition (the meter is increasing, when the taxi is standing still in traffic), and you have to pay a 50-baht surcharge. Anyway, taxi in Thailand is relatively cheap comparing to other countries. You can see how taxi fare in Thailand is calculated here. In short, you can expect to pay around 200-500 baht plus tolls. The problem is sometimes the taxi drivers refuse to turn on the meter and offer flat rate fare which is usually more expensive to the passengers. I do recommend you to not agree and try another taxi.
Airport Rail Link: This is a good option especially during rush hours. Airport Rail Link connects BTS Skytrain at Phaya Thai Station, and connects MRT Subwat at Makkasan station. So, you can reach many main areas in Bangkok without facing traffic jam.
Bus: There are a number of buses running from Suvarnabhumi Airport to several areas in Bangkok and also to popular destinations near Bangkok such as Pattaya, Chonburi, Rayong, Chanburi, Trad.
Public Van: There are a number of buses running from Suvarnabhumi Airport to several areas in Bangkok.
Hope the information helps