Exchanging money at Don Mueang Airport is easy but don’t get caught out by the lack of ATMs after you’ve passed through Passport Control.
When you arrive at Don Mueang airport there are several banks on the check-in side with ATMs, along with foreign exchange booths.
Exchange bureaus are also on the air side after you pass through passport control and security
However, there is no ATM machine on the air side. If you need to use an ATM to withdraw cash to exchange, go to one of the banks on the checkin side before you go though passport control.
Withdrawing money from a Thai ATM using a non-Thai card incurs a 150 Thai Baht fee levied by the Thai banks. If you need pristine US dollars for Myanmar (or Cambodia for that matter), you can exchange cash for clean US dollars at any of the exchange bureaus on the check in side or the air side.
Incidentally, there’s not much else air side at Don Mueang. There’s the usual duty free shops with perfume, booze and souvenir tat and several chain restaurants including McDonalds Starbucks, Piri Piri, Subway, Fuji, S&P and Black Canyon coffee. There’s also a Boots pharmacy
If you are looking for the absolute best exchange rate and you have time to spare in Bangkok, Super Rich (Thailand) in Rajadamri is widely regarded as consistently having the best exchange rates. The amount saved may not be worth the extra effort to visit their office, however.