I miss the days where I expensed the airport's short-term parking lot to the company. At $24/day, it's not something I could personally afford! Phx Sky Harbor Airport Parking is a great substitute.
The shuttle drivers are usually always friendly, quick and helpful. I have yet to come across any problems. I always call once I'm ready to be picked up so I never wait too long. A lot of flight attendants and pilots park here too so they're usually on the shuttle sharing a juicy story or two. ;-)
For those of you in the military, ask about the (non-published) military discount. $4.50/day. Can't beat it!!!!