The CU Art Museum is small but worth a stop if you are in the area. There are three rooms of special exhibits so it will be different each time you visit. The pieces are well documented and explained. Takes about an hour, depending on how interested you are in the works.
We came for the special exhibit. However, there is a room filled with "curiosities" like taxidermy, old Atari games (which they could play) and science equipment. There were even videos of MRIs done while people moved (talking, kissing, twins in utero) that as a physician I found fascinating. It is small, but free.