there is a massage place on Ruam Rudee in the little strip plaza with Circle bar I went to a while back (1 yr+) that I believe is still there. It was very expensive - something like BT 1000 per hour and no extras offered. The massage was ok but the prices of all treatments were at least double everywhere else so I never went back. I don't know who their clientele would be but it wasn't for me.
Your best bet might be to walk an additional 5 minutes to Suk Soi 2 for either Annies or Relax massage at the Raja Hotel.