Moab Utah and Arches Natl Park, whcih is right there
Bryce Canyon instead of Grand Canyon (it's prettier by far IMHO) but if you do the Grand, try the less touristy section. I think that would be the north rim, but do yourself a favor and get up BEFORE sunrise and go watch the sun rise over the canyon. At dawn, hummingbirds fly up out of the canyon to sip nectar from the thistle plants that grow along the rim. It's beautiful.
The highway that runs from DEnver in the general direction of Moab, via Vail, is a marvel of civil engineering and I think it's really worth seeing. I drove it many years back in my VW and had a BLAST taking those turns where the cliffs are too steep to cut a highway, so it's hung from the mountainside- literally- and the eastbound and westbound lanes are not side-by-side, but over-under.
Have a nice trip.