For those of you who don't want to move too far from Silom/Sathorn for a massage with sex, this seems a fairly-priced option:
H.E. Massage | Facebook
If you go their main webpage (no photos) you will see in English language, you get 3 hours for Bht600...at the bottom right of the main page. If you change to the Thai version, you only get 90 minutes for Bht600. Wow, that's a turn around! Of course, it is a misprint, but worth Sexitiler's trip down there to try it on:
:: H.E. Massage :::