Hi Joe,
This is good news. I'm glad you're making the trip.
I've actually never ridden the D&S so I can't comment on that, but I can offer some suggestions on the C&TS.
Chama has numerous hotel and restaurant offerings so I would recommend staying on that end of the railroad rather than Antonito, which is pretty desolate in comparison. However, that doesn't necessarily mean you should ride the C&TS eastbound out of Chama. Yes, the eastbound climb up Cumbres is famous, but on the westbound ride out of Antonito you get to experience a really interesting landscape transition from high-desert sagebrush to pinyon-juniper scrub to ponderosa pine forest to sub-alpine spruce and aspen forest to high alpine meadows, and I think it affords a better sense of the country and the wide-open spaces you're traveling through. It's a matter of personal taste, but you should consider both options.
When I visited Chama in 2014 I stayed at the Branding Iron hotel and thought it was fine: a good basic motel with clean rooms and friendly staff.
A good family-friendly place for breakfast or lunch in Chama is Fina's Diner, located at the south end of town (south of the wye) on Route 17, just north of the intersection of 17 and 64. It's popular with locals, which is always a good sign.
I would echo et&wnc's suggestion to take time to explore the Chama yard. The sheer quantity of rolling stock there is incredible. The C&TS is probably the most railfan-friendly place I've ever visited (other than the WW&F of course), and I spent an entire day just wandering in the yard and taking pictures.
I also agree with Chris Webster that Mesa Verde National Park is well worth a visit.
-Philip Marshall