Before going to Colorado, I made a list (from internet sites) of things to do in Colorado. Then I read all the activities to the kids and we voted on what sounded most fun. One of the things that sounded fun to the kids (esp. Michelle) was going to Tiny Town.
Tiny Town is a few miles outside of Denver, and it is like a small city made of miniature houses and buildings. Many of the houses have furniture, dolls and other objects inside. I really liked a flower shop that had a whole garden growing (plastic flowers and plants) and even had a list of things to look for...a mouse, a watering can, etc.)
Some of the houses were big enough that the girls could climb inside. (Most weren't but a few were.) There were 3 schools. There was a Fed Ex store, post offices, libraries, churches, houses, stores and so on. It really was like a whole town, but tiny! There was also a fun park that the girls played at for awhile. It was so much fun. Totally worth visiting. I think it may just be the part of our trip that the girls have talked about the most since we came home. (But they LOVED water world and the aquarium as well.)