Hi! We've just returned from our CO road trip, during which we spent one overnight in CB. We stayed at the Old Town Inn. It was perfect for us. Very nice staff, affordable rates (esp. compared to other lodging prices in CB), great breakfast, afternoon tea and homemade cookies, and a hot tub. The Town Park is right across the street, and the other (newer) park is a few blocks' walk away from there. My kids loved both...but the view of Mt. CB is nicer (unobstructed) from the new park.
Since we were there only 1 night, obviously we didn't do everything that could be done in CB. We walked up and down Elk Avenue, where all the shops/eateries are. We had great pizza and calzones at Secret Stash, which is at the very end of Elk Ave. Our kids loved the little hideout under the stairs there and all the groovy hippie decor. They had fun poking around in Pooh's Corner (toy store) too.
On an earlier trip to CB (sans kids), my sister and I hiked up Mt. CB. You can get there easily from town via the free shuttle. Apparently one can ride the ski lifts in the summer too.
Have a great trip!