I have used Avis for several years. I rent cars constantly from them. Sometimes I've rented two or even three cars in a single day (one at home, one at each of two cities where I had meetings) all domestic US.

Definitely get the wizard number/preferred. The car will be waiting for you, no need to sign a contract, just hop the bus/shuttle to the car lot (or walk in the few cases where the rental lot is inside the airport.)

When you return the car, they always print out a receipt, no need to go in anywhere. Very efficient, very smooth (except in SJC where I do not like their staff, not up to the normal Avis standards for some reason)

I have been very happy with Avis. When I have had problems, they've fixed them right away.
I recently called them and they sent me an Avis Preferred card (I learned about this program on this forum, where else?) and since then I get a free upgrade automatically to the next largest car. It's working out great.