If you are in Edinburgh, may I suggest you try a sauna first, cheaper, more choice and less nerve wracking. I would say that London Street and Blair Street come out on top, LSS is a wee bit cheaper. Closely followed by New Town.
You pay the room fee at the door LSS is £20 for 30 mins and £25 for 45 mins, choose the girl you wish to spend time with and then pay the lady in the room LSS is £55 for up to 45 mins.
You get a choice of girl, you know the girl you want is the girl you are going to get (no bait and switch) and no pissing about trying to arrange bookings.