We flew them from BKK-USM in September and flew them in Business Class, they operate some Business Class seats on their busier times, all I can say is WOW, they have their own lounge at BKK and a separate one for their Business Class passengers, which is just beautiful and they escort you to the aircraft. Once on board we were given the choice of hot or cold towels, and a drink. Then a full plated hot meal for the 45mins flight. It was one of the best regional flights I have ever been on.
If only QF/BA would do that on their regional flights, and Business Class on Bangkok Airways is only approx £20/$50AUD more expensive well worth the money.
Have a great trip.