It really doesn't matter which location you do it in.
I did the ACP program in Phoenix, that looks like a nice location, and I now work for ATP in Las Vegas, again, I like that location too. /ubbthreads/images/icons/smile.gif
Just one thing you should be aware of in Vegas; We don't do the short ATP program there. (The '2 training flights of 1.5-2 hours each' program.)
Else it's a great location to do your training in, you shoot your approaches into McCarran International. The examiners are nice and fair too.
But as I said before, do it where you feel like doing it. There are no major differences between our locations.