If you like climbing a lot, Flagstaff Mtn is real close in and a wonderful ride. It does get up near 20% grade in a few spots, probably 12 to 13% most of the way. If you like less intensity in climbing LeftHand Canyon is real nice. There are also some roads that top out in gravel which are in between the two of these in grade.
Pearl Street Mall is fun - on Saturday/Sunday there's a contortionist, a fire eater and a lot of great street musicians (in addition to the nice shops)
Be real careful where you park if you are getting around in a car. You're best off to get places on a bike so as to avoid getting booted.