The one real possibility for a rebuild would be Dolores - Mancos. Most of the line is just lying there ready to take ties and rails again. It's close to Durango and Mesa Verde, right off 160 and it is a relatively short 20 mile run between two quaint and well established Western Slope towns. The run is beautifully forested for much of it and crosses Lost Canon Creek with many small trestles. About an hour and a half each way, a family could spend a morning or afternoon riding the whole line and the rest of the day shopping in the towns or going to Mesa Verde.
Now, while we're dreaming let's get the 41, 340, 0402, Edna and Goose 3 out there from Knotts, along with their passenger train..........