Grand Canyon

The first question is, when are you going? If it's in the spring/summer, you will have the choice of visiting the North Rim, which is an easy two hours from Kanab rather than the 5+ it will take to reach the South Rim. It's much quieter on the North Rim, and just as pretty.

Unless you want to hike into the canyon, at either North or South, your activities are more or less limited to driving around to scenic points and oohing and aahing. But there are few places on earth better suited for doing that. You could also attend a ranger talk; those are fun.

Both rims are at considerable altitude (the North is well over 8000 feet, and the South 7000), so you might want to consider how that might affect your wife. For that matter, most of Yellowstone is at 7000 feet or higher, so I would keep that in mind as well. Most people, even with lung problems, handle the altitude just fine after a couple of days, but I would ask your wife's doctor.

While you are waiting for responses search this Forum for `Grand Canyon' and read the previous posts. Consider the train.

" I realize that this is not the best time of the year to see Yellowstone and to be in Arizona"

I've been there in all seasons. Its always a good time to see the canyon.

Honestly, the Canyon is what you see at the canyon. There's different views and small details to pick out. Going down into the canyon I guess you get a different perspective? Spending a day jostling around on the back of a mule/donkey doesn't sound exciting to me :) There's the touristy Watch Tower, part gift shop, part observation tower over near the South East entrance

I found Utah highway 128 to be equally spectacular. Same Colorado River, same fantastic blends of oranges, reds, browns in the rock. The bonus of UT128, you can pull your camper right into a BLM rustic site along the Colorado and camp there a few days. Only way you're camping next to the Colorado in Arizona is after riding or hiking down the walls, and then you're sleeping on the ground in a tent.