Wondering if anyone knows of a decent place to get an HIV/general STD test in the Rangsit or Lad Prao area? My medical Thai is nonexistent so somewhere that will understand English would be great (I assume many medical professionals speak it decently).

The best place is not in that area but rather downtown - the Thai Red Cross Anonymous clinic. Details in the pinned HIV thread.

 

There is no such thing as a single "general STD test", there rae different tests for different STDs. In addition there are different types of HIv test with different levels of accuracy depending in how long ago the last possible exposure was. For these reasons it is important to get proper advise/counselling as to what sort of tests you need, and while all hospitals can do these tests the quality of such counseling (if any at all) is often poor. TRC knows what they are doing and their counselors are quite skilled and professional.