I love the Silverton Northern drive, especially if you go all the way to Animas Forks. I don't know what it's like this late in the year, but the drive up Cunningham Gulch (Green Mountain Branch) to the Highland Mary is beautiful in summer. The Green Mountain Branch didn't go that far, but it is an easy drive until you get to the Mill. Avoid the Silverton Northern on weekends and holidays if lots of ATVs drive you as nuts as they do me.
Ridgway has remains of the original Rio Grande Southern roundhouse and turntable pit. There is even some rail spiked to ties. It's on private property, but isn't fenced or posted so access on foot is possible. Just be respectful and don't take artifacts. Kids playing on the site do enough damage without us adding to it.
I'm awfully fond of heading west out of Ridgway and touring the Rio Grande Southern. If you haven't been to Vance Junction or driven the Ames line (Road 63J), it is worth doing. When the road takes a sharp turn up the mountain, you can park and walk the Galloping Goose Trail on the RGS grade from there to the Ophir Loop. Of course, there is much more.