As little as 45 minutes should do. There is rarely a wait to check in for that flight. Airport is small so the walk to the gate is less than 5 minutes and only the early morning flights have any kind of line through security. Car rental return is also quick in that you just park the car in the nearby lot but you may have to walk in to finalize you car rental return at the agency's counter. The airport has nothing interesting other than a few historic photos and plaques about its long history. The key is to arrive as last minute as possible while still allowing time for them to get your luggage on the plane and before the America West staff (that check you in at the AS counter) vacate it till the 5:45 AS flight. If you have any carry-ons the MD-80's seem to have less overhead stowage than the 737's.