We went to Ouray last year, and it is well worth the price of admission.
The trails are stunning, the Jeep staff that run it do a very good job.
Definitely gorgeous scenery. Looking forward to doing it again.
I'd consider signing up but they're full and have a waitlist.
I don't think those organized groups "reserve" the mountain, so you could go on your own to any of those trails. You'd be sharing the trail with many other drivers, of course. Anytime during the Fall is a prime time with the San Juans, so you will not have any trail to yourself any way.
On a side note: anyone care to share their favorite camping areas near Park City, Moab, and Ouray?
I've camped at Echo Reservoir before, which is at the junction of I-84 and I-80, the latter going on into Wyoming. I've also camped at Jordanelle State Park, which is south of I-80, going towards Heber City on US 40. Both lakeside camping.
Near Moab, I've camped several times in some non developed spots off of Utah Highway 313, which is the road going to Dead Horse Point State Park and the Island in the Sky District of Canyonlands National Park. After camping along that road, head down Long Canyon to Moab and go through Pucker Pass, which is a nice downhill trail off of the mesa and under a huge chockstone bridging the road. Long Canyon is a mild off road route to Moab.
I've also camped at a BLM spot called Wind Whistle Campground, which is south of Moab along US 191. I've also camped at Hovenweep National Monument, which is a ways south of Moab, south of Monticello and near Bluff, Utah. Lots of ancient ancestral Puebloan towers and structures at Hovenweep. Hovenweep is a little out of the direct route, but worth the Native American history, IMHO.
Near Ouray, there is a nice campground just south, called Amphitheater CG.