Eleven mile is a large reservoir by Colorado standards and has tons of campsites, all around the lake from great walk-in tent sites, lake shore and small to large loops.  One section of the park has great trails in the trees, but the majority is in open plains which can sometimes get windy, but still is a great place.  The facilities are well maintained, all sites have a picnic table, fire pit and two loops have electrical hookups.   The central area has water spigots, a shower house, flush toilets, laundry and a dump station.  The other campgrounds have vault toilets and hand pumps for water.  

Just outside the state park boundary is a small convenience store for grocery (limited) and angler/fishing supply.  The lake can get busy in the summer, but it never seems too crowded.  Also, like many state parks they do have an educational program and offer small exhibits at the amphitheater on the weekends.