We have a layover of about 6 hours on SUnday October 6--waiting for our redeye. Have any suggestions? If we rented a car, would we find something worthwhile to do for a few hours on a Sunday evening?

Phoenix's primary asset is its weather. People who move there do so because they enjoy the outdoors, sunshine, etc.
PHX is very short on culture, museums, etc.
The best thing you can do in PHX witha few hours, IMO, is to go walk up one of the mountains like Squaw Peak or Camelback Mtn. Stretches your legs, gorgeous views. But you have to be in decent condition.
Shopping in PHX, like most large cities these days, has become pretty generic.

If there's enough time, tour Taliesin West in Scottsdale, the Frank Lloyd Wright school & home. It's fascinating and well worth seeing. There's tours of varyig lengths starting with 1 hour. Check this website for info http://www.franklloydwright.org/inde...n=taliesinwest

Donna, Here are some suggestions:

1) Phoenix Zoo/PHX (Near the airport)
2) Heard Museum/Downtown PHX/Central Ave.
3) Desert Botanical Gardens/PHX - near the airport.
4) Frank Lloyd Wright's home/now a museum/North Scottsdale
5) Gamble in the many Casinos
6) Take a drive up to town of Carefree, visit the many shops.
Enjoy.

If you are waiting for a redeye, then I don't think any of the places previously suggested would be open. I would bring a good book and read.

The Desert Botanical Garden is close to the airport and is open until 8 pm every evening, so it might work for you. It's an interesting place and a good chance to stretch your legs before your next flight.