I would say that you really need to identify the purposes that the sidearm will be used for.
As you know, possessing a firearm on National Park property can get you an All Expense Paid vacation to Club-Fed.
Okay... So... Are you going to be packing the pack gun for 2 legged, or 4 legged vermin?
I'm assuming that the Bear's, and Coyote's in AZ would be the main concern. The occassional 'Border Bandit' and general Bad Guy might also be considered.
I like the performance of the 10mm, and the potential of the very hot loads in 10mm. Against small Bear's, the 10mm might not be any better or worse than a 357, but against the bigger Bear's, neither will be enough to instantly stop the problem if you find yourself in a bad position. In that case, I don't think any reasonable handgun caliber would get you very far, so you have to weigh the benefit's yourself.
Personally, I don't see any advantage of a revolver over an pistol these days... I do see plenty of advantages of a Pistol over a Revolver though... Therefore, I would much rather prefer to have slimmer profile, and improved ammunition capacity/storage that the Semi offer's.
I think if I was considering something for this purpose, I'd be inclined to consider a Glock 10mm, either the Full, or Compact sizes, maybe even both. Considering that I am not a big Glock fan, that might say quite a bit. While I don't feel the Glock offers the accuracy that other choices may, I would imagine that they would be more than sufficient for the purposes intended...
Anyway, good luck with your decisions...