Well, there's always OP:LC, if you're willing to spend the money. There was also a thread about Eastwinds, a big super authentic milsim in Kansas. It's pricey as well.
As far as things to do around here, Team Phantom is hosting a game near Tucson next Saturday. There's always a couple of pick up games posted in the RSVP forum.
There's two indoor fields in Phoenix. Tempe Paintball and Vanguard. Vanguard is a great field, but you're dealing with a terrible crowd and horrid employees. Tempe is smaller, but runs great and the staff is very friendly. There's usually an informal game on Friday, with a couple of people from the boards showing up. Lately, more people are coming out for airsoft there, so Fridays are a good bet.
Hope this helps.
