I have to head out to Colorado Springs, CO for work the first week of October. I have to work Monday - Wednesday, September 30 - October 2. I plan to bike in Fruita or Moab on Thursday, Friday, and Saturday, October 3, 4, and 5. Fly home from Denver on Sunday, October 6. I did the same thing last year and spent all 3 days exploring the trails in Fruita on my own (Kokopelli Loops and 18 Road Trails) so I am somewhat familiar with those trails. Had a great time!
I've never been to Moab and it is another 1.5 hour drive west from Fruita, but I would consider going. Fruita is already a 4+ hour drive from Denver, but worth it! Rented a great bike from a local shop in Grand Junction (I think you can fly there) and brought out everything else I needed. The scenery is spectacular....see pics below all taken by me on the trails (except the last one, which I took in town).
There is some info on the trails I rode last year here: http://www.mtbproject.com/trail/290187