I remember several of these spas fondly.
Babylon was where I first met August, who moved to 27MS after Babylon closed (or maybe a little before it closed?).
Moon Boy was indeed the name of the place on 25th off 6th. I remember it being Moon Boy in contrast to Sunny Boy on 27th, before it changed to 27MS and then moved to the other end of the block to its current location.
I don't recall the name of the place on Lex at 28th but I remember my experiences there very well. They advertised on Craigslist. I used to get a massage there and then go across the street to an Indian restaurant for lunch or dinner. I never went to the other spa nearby though. I believe that one opened afterwards (or marketed its itself to the gay community afterwards) and I felt loyal to the first place.
A few more no longer with us:
Top Men Spa (35th and 7th, I believe)
Hero (50th and 9th?)
Grandee (56th and 8th)
28 Mens Spa (28th and 6th)
Alpha Male (west side/midtown - I don't recall the cross streets as I only went once or twice?)
New Yorker on 6th between 30th and 31st.
24 Chelsea Spa on 24th off of 9th Ave (not to be confused with Chelsea Men's Spa on 29th and 6th).
There was a "bodywork" spa in the basement just north of 14th St (not sure if it was 15th , 16th, etc.) and I think they had another location with the same name in HK on 10th Ave?
There was a place on 57th St, maybe between Lex and 3rd? Lots of older, muscular Asian masseurs there. That was probably about 15 years ago. It was one of the first HE type spa I every experienced.
There was one on E 53rd, maybe between 3rd and 2nd Ave? Can't remember the name though.
And there was a spa near Grand Central, not far from the old Shangri La, except this was in an office building. It always felt a little strange to go to this location with so many "legit" workspaces just down the hall.