Gordon, The Rio Grande Pagosa Northern became part of the D&RGW in the early 1900's. This route went to the west of Pagosa Junction, and follows Cat Creek road north, meeting highway 160 at Dyke, then went east to Pagosa Springs. There is some grade visible south of 160 opposite the resort on private property. Another branch ran south of town down Trujillo Road almost, but not quite, making a loop from Pagosa Junction to Pagosa Springs and most of the way back to Pagosa Junction. This line was abandonded in 1935, so any remnants are hard to find, however, if you look hard enough, you can still see evidence. The current roads use much of the RR right of way.
The Pagosa Springs Depot is still standing, now a private residence. It is a block or two south of (behind) the City Market at 8th Street and 160. Drive around this area a little and you will find it. Seen from one side, it is unmistakable as a depot.
Is it worth it? I spent an afternoon on a "Pagosa Trek" two years ago. This trip was organized by the Silver San Juan Division of the NMRA and hosted by the local model RR group. I really enjoyed it.
There are a few reference books I'd recommend; Logging along the Denver & Rio Grande by Chappell, Tracking Ghost Railroads in Colorado by Robert Ormes - both out of print. Pagosa Lumber Company Railroads and Sawmills by Robert Sullenberger is available in the local Pagosa Springs Bookstore.