I worked as a locomotive engineer for both the C&TS and the D&SNG. I have to admit up front that I'm a locomotivecentric person--that is, I never cared much for riding the trains, but I sure loved firing and running the locomotives. After running on the D&S for a couple months, I took an opportunity to ride the train, and the first thing that struck me is the limited view of the scenery from the coaches compared to from the locomotive. The problem is that the windows on the coaches are too low, and much of the railroad's dramatic scenery is the towering peaks viewed from the bottom of the Animas canyon. Consequently, while riding a coach, you find yourself constantly bending down to look up. These coaches would be fine on the C&TS where much of the road lies much higher on the landscape and the views are more panoramic.
For your trip on the D&SNG, I recommend you secure a seat in one of the "open" cars. These cars have roofs, but the sides are pretty much wide open. It's a bit of a gamble with respect to the weather, especially late in the fall, but I think you'll enjoy the views more and will get a better feel for the railroad. You'll also be pelted by more hot cinders and eat more smoke. Another minor problem with the open cars is that you can get into disputes with other passengers over blocking their view. The bench seats in the cars run fore and aft, and on the way up to Silverton, the people on the west side benches all want to come over and stand on the east side of the coach to view the Animas River at the High Line and at other points, thereby blocking the view of any of the people on the east side benches who thought they were going to be able to remain seated and still enjoy the scenery. Minor annoyances and maybe good lessons in human behavior for the kids. Be patient. If you don't get a good view of something on the way up, you'll probably be able to check it out on the way home. Most people are less edgy about getting their money's worth by then and are less likely to be so possesive of their view.
In the years since I left the D&SNG, they've built a new "dome" car which I'm sure offers better views of the scenery, but it's probably go'n cost you a little extry.
Hope you enjoy your trip. The fact is, there's no way you can't enjoy it.