You may find this Thread at the TG forum helpful:

http://www.flyertalk.com/forum/thai-...non-f-bkk.html Read A_Lee's post#6.

Personally, I like the SQ Silver Kris Lounge the best (if you're *G on a *A flight, you may use this lounge) and the only detracting feature is the lack of an on-site toilet facility.

TG and SQ are the only *A lounges at BKK.

For TG, as *G, you may use the Royal Silk Lounges at Concourse C (East & West), and E (East). The one at Concourse D is unavailable for *G. Concourse A if domestic. Yes, you may also use the Royal Orchard Lounge at Concourse E (West). I have been to most of them and I don't think any one is better (or worse) than the others.

SQ's SKL is the best overall IMHO.