When in Keystone, make some time to do the alpine slide. There are nice views from the top and the snack shop serves great burgers.
The slide down is really fun. Special plea for parents: if you have a child who is not a daredevil, please send them down the slow track. I chose the fast lane, but still got stuck behind a terrified little girl whose parent had sent her down that lane and I had to go at a crawl for the second half of the track when I quickly caught up with her. I went two days in a row and it seems chronic for slow riders to go down the fast lane.