Jeremy,I wouldn't recommend streetwalker action in Vegas, given Metro's zero tolerance to the whole idea.  First, there are very few around.  Second, if you do find one, they are either part of a Vice operation or at worst a high risk group (disease).  If you like the thrill of seeing the provider first, I would recommend trying the hotel bars.  But, even this comes at a risk.  My first pick is to always use a reputable independent provider.  Hope this info helps.