I've only experienced soapy massages in Thailand and from my punting experience, Thai girls provide the best service.
Just go to the ratchadaphisek area and pick out one of the soapy massage places below, you cant really go wrong. Since many of them are in the same area, you can just walk in, check out the girls (there is usually a stand in front with all the girls sitting, and the more expensive "prettier" onces are called sidelines sitting around the lounge/bar area), if nothing hits the spot then walk out and go check out the next soapy place.
The standard service is 90 minutes (officially one pop, but depends on the girl, some allow multiple pops, some you have to negotiate and pay extra), you're taken to a room and given a nice hot soapy massage in a bath tub with bbbj, get out dry off and get on the bed and you can use your imagination from there.
Hope this helps, feel free to message me.
Amsterdam
Alaina
Emmanuelle
The Lord
Copa Cabana
Colonze
Utopia
Poseidon
Nataree (a bit cheaper and lower end)
For more check out
www.thaimassagemodel.com