When I first started flying to Bangkok in 1980s, the old Don Muang airport was a bit dowdy but served well. Then the new Suvarnabhumi Airport was build, relegating Don Muang to a domestic and no-frills airport.
Coming back from Bangkok last, there is now a no-frills S terminal at Suvarnabhumi and it is top-notch. It’s got all the shops and glitz and gardens. Just no people. It just opened and the carriers haven’t moved all their flights there.
It’s nice but it took almost twenty minutes to get there, even with a train ride, from the main Suvarnabhumi terminal.