Burning Bear camp ground is on the south end of Guanella Pass in central Colorado. It's a small campsite with maybe a dozen sites where we had a large buck and a doe greet us early in the morning. The view is amazing. This photo was from the edge of camp at sunset in July 2017. (photo by John Swift - johngswift.com)
The Englewood Rec Center has a full-featured recreation facility with room for all sorts of activities. They have an indoor pool and with some small notice, they have been very helpful with getting swim checks completed and signed off by their certified lifeguards. They also have a gym for basketball, courts for racquetball/squash, and a running track.
There is a great (although kinda small) climbing wall that offers challenges for all the boys... bring your Climb-On-Safely trained adults to do belay, because they only have one person on staff normally...
Peaceful Valley Scout Ranch is one of two Scout Ranches for the Denver Area Council. Located south-east of Denver only a short 90-minute drive, PV has three separate camps within the Ranch: Camp Deitler, Camp Chris Dobbins, and Magness Camp for Cub Scouts.
Bear Creek Lake Park has multiple camp sites, with a wide variety of amenities, including RV spots, and a large group campsite. Reservations are required in advance (WAY in advance) and need to be booked on the Lakewood, CO Parks Department website. Once you go to their site (at this point) it will not show any availability after the initial reservation. If you mess up and want to make changes, you will need to go directly to the old-school phone call.