Finally found a lounge I like at BKK so time to jot down some thoughts:

Thai Airlines Royal Silk/Orchid/etc are ok but the main one is generally very full, and the food tends to be pastries and ok dim sum. There's a cocktail bar at the main one but it looks pretty sparse. Often pretty noisy.

Cathay Pacific lounge is nice with good fresh-cooked dimsum. OK coffee bar, and nice recliner seats with a view of the tarmac.

JAL lounge has a very 80s vibe. Dark leather and weird canapés made out of olives and crackers. Notable Japanese style toilets.

Singapore Kris Flyer - packed but very civilised. By far the best selection of food I've seen in BKK lounges - really tasty buffet, cheese board, cocktails.

Bangkok Airways Blue Ribbon - super attentive staff, limited selection of fresh cooked Thai food.

Where else is worth a visit next time passing through?