I concur with the above comments, although I've been on a few domestic Airbus A300-600 V3602's that have reasonable business (J) seats. However, I have been amazed that their front-line Royal Barge transpac 47-400's still have threadbare J-seats w/o modern in-seat entertainment.

Regarding the lounges, Thai has two Royal Orchid Executive (Business) lounges. The 'main' lounge is near the northern end of Terminal 1 (left turn after immigration... a bit of a walk). A second, smaller lounge is just south of immigration. A large number of domestic flights use the bus gates on the lower level of the terminal, accessed by the stairs/escalators which are located on the left, prior to reaching the main TG lounge.

As Rudi noted, the main lounge does indeed have a self-serve counter. A small selection of liquor is available, day and night