I tried out Aviva Massage on Sukhumvit Soi 8 and was very pleased with the service. Its on a side soi/alley off of Soi 8, however they have a sign on Soi 8 that shows you the way.
It is not the cheapest at 400bht for an hour oil massage but the rooms are very clean and the girls are all above average.
I chose a girl named Amp (not pictured on the website) and the massage she provided was far superior to any of the rub joints I visited in Pattaya. I would have been pleased even without the happy ending.
Full service is available, however, I believe price and services available vary by the girl. Ask the Mamasan.
During the massage, it started pissing down rain and it had not let up by the time I was ready to go. The girl got 2 umbrellas and walked with me 2 blocks to the nearest mini mart so I could purchase an umbrella, and not get wet. I thought that was nice customer service.
Here is the website:
http://www.avivabkk.com/