Jim,

Why not check out the North Rim of the Grand Canyon this time? The North Rim is much more remote than the South Rim, it is about 2000 ft higher in elevation so will not be hot that time of the year. (70s or so at the top). There is fantastic hiking both on and below the rim, and great photography. It is harder to get to from the Phoenix Airport, but well worth the extra drive.

Bryce Canyon is also cooler due to it's high elevation. I think it is well over 8ooo feet - we froze there a couple years ago camping in mid-March.

Just a thought.