I too get bored shooting at paper. That's why I usually load up the car and head to the hills - I usually shoot at my metal reset target, I just love that "ding."
However, I don't understand why folks cannot find places to shoot round Denver and I think I need to clear this up. I've lived here all my life and things have become more congested, but it ain't that bad. I live in the southwest suburbs and used to make the short drive to the Rampart Range area, but they've now made that area a motorbike recreation area and target practice is prohibited in most of the area north of Devil's Head. So, what did I do? I just found another place, my own little place, using my topo maps and my local knowledge of the state. I now primarily shoot in Pike Nat. Forest all by my lonesome - and it's less than 45 min. from Denver, the same time it would take to get to my club out east.
Basically, what do you need to find a place? A clear area with a backdrop that's 150 yards from a roadway or occupied area. Well, geeze, that's easy as the state's chaulked full of backdrops (mountains) and open land (Nat. forest, BLM). Park the car a walk a few minutes, you'll find them. So, get out your maps or GPS, get in that car and find your own little place to shoot.
For those that want to be told where to go, or want to shoot around strangers, and live in south Denver, here is one of many. Sorry, I don't have the coordinates in front of me. South Deckers Rd (RD. 126) from Buffalo Creek to Deckers. At about the overlook on the east side of the road south of FR 550 (overlooks the valley to Long Scraggy Peak, this is south of the long straight section where the Colorado Trail crosses the road) there are at least 3 places that folks regularly shoot. All 3 are less than 1/4 of a mile from 126 and are direct hits (meaning no extra turns once turn off 126), and the most used is on the west side and has a huge manmade backdrop - you cannot miss it once you exit the main road! I don't use them though, I prefer to be alone and not have to encounter others when shooting.
As far as my own little place, sorry, find your own, there's plenty of them out there in this wide-open and beautiful state.