Baht rates here usually beat the airport banks by a few satang.
Superrich Thailand at Suvarnabhumi sits airside in the Main terminal, so you can swap cash after security instead of backtracking to landside counters. It’s the green-brand Superrich, not the orange one, and rates generally track their downtown branches, just with a small airport premium compared to the Ratchadamri HQ. If you forgot to change money in town, this is still better than most bank booths along the Main concourse.
You’ll mostly see lines during daytime bank hours, roughly 09:00–20:00, and shorter waits later at night when the long-haul banks of flights depart. Staff handle the usual airport mix of USD, EUR, JPY and CNY without drama, but more exotic currencies may get a worse spread than what you’d see at a city Superrich on Ratchaprasong Road. Bring your passport; they follow Thailand’s standard ID rules for higher amounts, especially anything north of about 20,000 THB equivalent.
Rates on the board update several times per day, and the buy–sell gap on major currencies usually stays tighter than Thai bank counters a few meters away. You can swap small leftover notes back into baht here before heading to your hotel, or convert spare baht into USD if you’re exiting via the Main terminal on a late-night flight. Tip: check the official Superrich Thailand website rate on your phone first, then decide how much to change here versus in town next trip.