There wasn't much to choose from when flying to Samui in the past, they didn't have the A320 family before mid 2000 so I've flown a lot with them in ATR-72 and often in rainy conditions.
I've even flown with them in a smaller turboprop, can't remember what kind but most probably the ATR-40. Kaki brown, had not yet been painted in Bangkok Airways colors.
That was before Samui airport was officially opened and the runway was then only a long unpaved sand strip!!
The single terminal building was a tiled floor without roof, the arrival and departure sections of the floor being separated by chains.
The hand written ticket looked more like something you get in a shop and not like an air ticket, price was 1700 baht for a BKK-Samui return trip if memory serves me. No daily flights, one flight every 2 or 3 days.