During your trip to Thailand, you may have to go from Suvarnabhumi Airport to Don Muang Airport or vice versa, most low-cost airlines and domestic flights being based at Don Muang. Conviently, AOT (Airport of Thailand) offers a free shuttle bus service connecting regularly the two Bangkok airports. To board them for free, you must have a flight ticket from the other airport. Otherwise, the fee is around 60 THB.
At Suvarnabhumi Airport, free buses to Don Muang are at Passaengers Terminal on the 2nd Floor, Gate 3.
At Don Muang Airport, free shuttle buses to Suvarnabhumi are located on door 5 at Terminal 1 or door 12 at Terminal 2 (follow signs for ''shuttle bus'')
The shuttle bus from Don Muang Airport drops passengers at Suvarnabhumi Passenger Terminal at 4th Floor, Gate 5.
Count 1 hour 30 minutes to reach the other airport. It is often less but the journey time depends on traffic.
There are two bus lines connecting Don Muang Airport to Bangkok city. They allow you to go to BTS Mo Chit station or to join Bangkok Northern Bus Terminal (Mochit) or Victory Monument in central Bangkok.
The Bangkok Skytrain is called BTS. The trains have air condition and let you go over the heavy road traffic in the capital but you can not go everywhere even if connected to the Chao Phraya Express baots, it can let you go to major temples in Bangkok.
Taking the bus to get around is clearly not the easiest mean of transportation to use for a foreign tourist in Bangkok neither the fastest one but it's the cheapest one. Bangkok bus network is wide and you can go almost anywhere but just need to be patient.
Only Thai city for the moment to have a metro (there is metro project in Phuket), Bangkok is the city in Thailand that offers more choices of public or individual transport (metro, bus, boats, tuktuks...). No, there are not just tuk-tuks and pink taxis to get around Bangkok !