As far as I know there isn't an arrivals lounge in BKK...
In the domestic terminal, it all depends on the airline... facilities can be pretty good. No lounges per se, but free internet, orange juice, fruit cookies/biscuits etc. on some of the smaller airlines. Never had any experience of Thai domestic.
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by gnaget:
Right next door there is a Thai F class lounge, which is * Gold. </font>
The Thai F lounge is for F only. I've been dismissed from the door many times, as a lowly *G.
Your main choices are the Thai Biz lounge (big and busy with good food selection) and the Silver Kris Lounge (small, often quiet, poor food selection). I believe there might be one or two more choices, but have never ventured far.