Most of the "call girl" types that you see in the multitude of publications that litter the strip and advertise such action have been checkmated by hotels' efforts to keep them out of their establishment by making a room key necessary in order to operate an elevator. You can possibly meet one by chance in a casino or whatever but that is risky to say the least.
I'd either make the trek out of town to visit a brothel or I'd go with Oh_Yeah's advice and partake in something of the massage parlor/jack shack nature. Don't succumb to the temptation to get some girl to come to your room. Way too risky in the first place and not worth the money (at least that's what a friend of mine told me)!
Good luck and I hope u find a way to get your nuts off regardless....even if it has to be the self-service method!
:1orglaugh