This one is on Las Vegas NV. I hope to get some more up soon!!!
OK.. Maybe you are going to go to Vegas to gamble or act cool or whatever.
All of that is fine but as you might expect, there is an unusually high percentage of douche bags. They are there to act even cooler than you.

My suggestion is to put some time aside do some jamming. It will be way funner and cheaper; plus you will find amazing terrain that you simply can't find any where else.
I was there for about a month before I had to head out to San Diego for a work event. In that time I got a good feel for the city. There is a pretty well established PK/Freerunning Meetup group there but it's membership is exclusive and I had a bit of trouble getting a hold of any one. I think they are mostly focused on the professional bases stuff on the sight. It looked like there were a few other groups and if you try harder than I did you can probably find someone to jam with.
Regardless, if you find someone to jam with or you go it alone, this place is way fun. There are tons of new developments all around with interesting and pk friendly architecture. Tons of good parks as well. And the strip is insanely fun. There aren't too many people there... Depending on whats going on because of the economy. So you should have some good room to move.
As long as you keep moving a bit you shouldn't get in too much trouble from the security guards (I only got 86ed once from a mall area cauz I was waiting around and jamming while waiting for a friend.)
Some places I hit up included:
-The mall across the street from the Wynn
Bad ass out door area with a smooth marble like floor great for sliding under rails, long hand rails for precision balance, Tons of level changes and some pretty OK corner type gaps.
-Inside the casinos are also great
Almost all of them have some fun things (stuff you won't find anywhere else.) Watch out for security though.
-In front of Treasure Island and around the side
There are rope balances posts and rails to balance and gap all around the front area. There is an artificial rock wall around the side that has good level change and area to work. Even further around the right side of the building there is a back handicap entrance with tons of rails that looks like they are never used. These rails are awesome for practicing flow precisions.
PS.
If you are going to go to shows and stuff Circus De Ole is a clear choice. You will always be satisfied and it is $$ well spent. I've seen KA about a year ago and some other one I cant remember the name, a couple years before that, in Portland. They were both amazing. This time I saw the Beatles one "Love" and it was cool but the the stunts and stuff were lacking. It was mostly music and visual based. I haven't seen it but I've heard that O is the most spectacular but it is really water based.