The REI store is really cool and in Denver, you might want to check that out if you're into outdoorsey things. There is also an air museum just outside of Denver that IMO is pretty decent, it's called "Wings over the Rockies". If you feel like driving a bit, Ft. Collins is a really cool town about an hour north of Denver. Fat Tire beer comes from there, and downtown has a bunch of pubs and taverns. It's a really cool area.

My dad just moved to Ft. Collins, so I don't know a whole lot about the area, but I like it a lot there. Real relaxed feel to the place. If you do end up there, check out the Charco Broiler steakhouse, best steak I have ever had!