Got kids?Go tubing. It sounds, well, juvenile, but spinning 360s in a rubber tube down an iced-over track is belly-ache-inducing fun. Plus, Keystone's tubing course on the top of the mountain is one of the best in Colorado, so if you're going to get doing it somewhere, it might as well be here. A lift serves some of the longest and steepest tubing lanes in Colorado from 12–4 p.m. (open until 8 on night-skiing evenings).
Tip: Make reservations. Tubing can sell out days in advance.
Admission: $22 or $18 for kids 6–12 (there's a 36" height requirement)