TG Lounge at KTM
The Thai Lounge at Kathmandu gets my vote. Small, not much in the way of food (Good food seems to be one thing TG lounges do well) and sectioned off from the departure hall by some kind of partitions, rather than being in a truly separate room.
It's actually more pleasant and spacious to stay in the general area...until they cram you into the pre-boarding lounge that is....