Colorado Springs (my hometown) has a lot of great trails, but if you are making a special trip, then I suggest submerging yourself in the best MTB’ing experience possible and for that you need to go to the MTB mecca, Durango. The Hermosa Creek Trail, north of Durango would be my first ride. The best place to start is at the northern end behind the ski area and finish up above the village of Hermosa. (The LBS’es have shuttle services available for a reasonable fee). From Hermosa, you are just a few miles from Trimble Hot Springs. You could literally spend your entire time in Durango and never ride the same trails twice. From Durango, Moab is not that far but the heat will be pretty intense. The best time for Moab is in the fall. If you are not going to be in that area, then I recommend Buffalo Creek and the areas mentioned above by arnolda14.