Capitol Reef National Park

you mentioned wanting to do the Shaffer Trail and that brought back many great memories.  My wife and I biked the complete 100 mile trail on 2 different occasions. We went with a group of 5 others and had 1 support vehicle. We did it in 5 days each time, traveling about 20 miles per day on our bikes. we carried all of our food, water and camping  gear in the support vehicle. each day a different person had to drive and the rest rode bikes. it was a great trip-both times.

You have to have  a permit and the camp sites are reserved along the Trail. There are 2 horrendous climbs-Murphy's Hogback  about midway and one at the very end.

check the time that you want to go-there are a lot of jeep safaris out of Moab during certain parts of the year.
Vann

We really enjoyed Capitol Reef, but Canyonlands National Park is right up there with Zion for me personally.  The rock formations and colors are simply magnificent, and there are virtually no crowds.

I agree, we did the Circle Tour through the national parks in and around Utah. I like the outdoors but not sharing with 100's of people at the same time. Try going to the others in middle to late September when school has started.