Hi mate,
I've been going through a parlour phase myself so I can help you. Which is nice as I'm usually the one asking the questions
Baker street:
Has a few here. Natural ways is great and will offer he as well as full body to body with he.
There is a Thai place next to it which is nice also, but hit and miss with the girls, but the massages are good.
There is also a massage place opposite the side entrance to Street, also excellent and will offer everything after a good massage.
Piccadilly :
Chinatown has loads... Your pick really!
There is one, I think it's called sensual touch. Google Thai massage piccadilly and it's number 74 Shaftesbury Ave I believe. It is very nice inside and gives a great massage. A little on the expensive side though.
Let me know how you get along.