It's great to see folks plannng to do things the right, and legal, way.
Ski's tip on phoning local district offices is a great one. For National Forests (NFs), you're looking for "Ranger District" offices, where each named NF is divided up into several Ranger Districts. You'll find the Ranger District offices listed by address and telephone numbers on that NF's official US Department of Agriculture National Forest Service website. The Bureau of Land Management (BLM) has local district offices, too, but I am less familiar with the administrative subdivisions of the BLM. I have, however, successfully engaged local BLM personnel by email and telephone relative to very specific road conditions and camping sites in far southwest Montana.
As to specific areas in CO-UT-WY, where to start? I'll hazard a guess that there are over 20 million acres of NF lands alone spread across the 3 states. What I suggest is becoming familiar with NFs first, and that can be a wholly online study. Just go to, for example, the Shoshone NF website and start clicking on maps, camping and recreation, and other tabs. Look at the NF's current Motor Vehicle Use Maps (MVUMs, available online), as a given NF's road system is very extensive, involving hundreds of roads and trails, since at any given time access is restricted for one area or another, and major seasonal restrictions are shown on the MVUM.
With some familiarity of NF units under your belt, invest $20-25 in a Benchmark Road and Recreation Atlas for each state you're interested in exploring. The Benchmarks are superb tools for planning, showing accurate and specific plots of NF lands, BLM lands, other Federal lands, and state lands. They show recreational areas such as designated NF and BLM campgrounds, roads, trails, streams, lakes, etc. While they're not topographic maps, they are excellent shaded-relief maps with many "spot elevations" which give a very good picture of the topography. Combining a downloaded/printed MVUM (or, having the MVUM on a reliable digital device), a Benchmark, and a good GPS with which you are good at using (and not trusting blindly) makes for a fine set of tools with which to plan and execute some serious Rocky Mountain off-highway exploring.
Enjoy the planning and the exploring.
Foy
