Eh, don't think you've been in Phoenix in the summer. Nights are still triple digits, which is the main thing that makes the summer so brutal.
Phoenix regularly has overnight lows above 90F. It's pretty bad.
The problem is all of the concrete. Get outside the heat dome and it cools considerably. You just have to rethink the building pattern. (White roofs with water collection would be a good start.)
Agreed. I lived in the southeast valley for 16 years. At the start of it, we were fairly near the edge of the sprawl, and now you have to drive another 20+ miles to get out of suburbia. It's definitely had an effect on temperature, particularly overnight.