Casual float w/geology
I just floated the Colorado, Fruita to Westwater Guard Station: 2 days, 1 camp. You can also put in at Loma (4 miles shorter). Nice redrock canyons. Eagles, wild turkeys, geese. Easy 2-day drift that can be stretched to 4+ days with sidecanyon hikes.
Downside: Fruita State Park charges $5 every time you breathe. Don't leave valuables in cars at Loma. Railroad tracks by the river for much of the way. Can be crowded on weekends (with campsite poaching at Mee Canyon and Blackrocks).
There's a nice day float downstream, from Dewey Bridge to the Takeout beach above Moab. Super views, a bit more in the way of rapids, and most often lots of people (the old campsites river left are now BLM campgrounds and there's lots of private land development).