Thank you Pong for your guidance.
The site from which I often glean interesting massage information is:
TMM Society - Index
Scroll to the bottom of the main page to get the links.
While some of the links are dead, others are gems..particularly for Khon Kaen and Udon for example.
The massage place in Bangkhai you refer to is possibly Bangkai Thai Massage in Phetkassem soi 62/1. That is near the market. They have a new branch at Suksawat soi 29 called Suksawat Thai Massage. I have seen both but never gone inside as didn't see any boys I liked. Although their Hi5 page does show some do-able boys:
hi5 - Bangkae Thai Massage
The place I used to frequent near The Mall Thapra is in Ratchada soi 12 called Smart Bank. I believe it is still there. It was pretty good if you liked the boys on offer.