Colorado Springs is wonderful! Be sure to go to the Garden of the Gods and Pikes Peak. Depending on the age of your kids, you may want to check out the North Pole, a cool amusement park. http://santas-colo.com/
Manitou Springs has a great collection of antique shops to poke through.
Mesa Verde is fascinating if you have the time. You really get a good feel for the cliff dwellers,etc. The Great Sand Dunes are amazing as well.
With both Mesa Verde and the Springs area, be sure to drink a lot of water due to the altitude. If anyone starts to feel lightheaded from the altitude, especially going up Pikes Peak, give them a few Tums. Tums, for some reason, helps with the symptoms.