Shouldn't be. In fact, getting a hotel will be much easier and also quite a bit cheaper because you will be in the 'shoulder' season, and kids have gone back to school. You might want to try the Redstone Inn as an inexpensive yet popular place to stay at in Moab. In Moab area, it'll still be warm and dry, but not as hot as July Aug. Trails and parks will not be crowded during the week, or even the weekends. CO, it's between the summer and ski season. Should be able to find a place the day of, or day before on your phone (download booking.com). If you go to CO, the leaves start turning, but that is more 'late' september, and it's really spectacular with snow capped mountains in the background if you can time it out right. If you are limited on time, maybe put CO on a second trip out.
