"Just a few miles north of there is place called SNOW FLAKE... Wonder how it got it's name..."
It's name comes from the two gentlemen who founded it.... Mr. Flake and Mr. Snow. One of Flakes grand (or great grand), children is the Senator from Arizona. Show Low (6,000') does not get a lot of snow, usually a few inches several times a winter. It takes a major front and they are easy to forecast. Between Show Low and Payson you will find yourself at nearly 8,000' and there can be heavy snow on that stretch of 87.
We've driven the Salt River Canyon dozens of times and the road is so well engineered I don't see it being anything but spectacular.... as long as you have enough truck. :B
Dropping down/or climbing the Mogollon Rim is just was steep as the Salt River Canyon and also a spectacular drive. From Payson down to Mesa on 87 you will encounter lots of steep grades but nothing that you should not be able to negotiate at 50-55.
As always.... Opinions and YMMV.
:C