If you're a fan of ballparks, which I assume you are, I would check out the National Ballpark Museum right across the street from Coors Field. There are all sorts of cool artifacts, and it's definitely worth a visit. I would also recommend making the short drive to Boulder for the afternoon one day. It's a really neat college town with plenty to do and eat.
It's been awhile since I have been there but always loved going to Lodo's before a game. As Cam said, check out NBM!
Hey Brad! I also recommend the Ballpark Museum and Lodo's!
Colorado, one of my favorite states after my road trip out west last year! Make sure to go to the mountains if you do go to Boulder. Also, if you have time, Colorado Springs is a 45 minute or so drive away and it has the Garden of the Gods, one of the most unreal sights I've ever seen.