I'd highly recommend the trip from Denver to Glenwood Springs in the winter time. Awesome scenery. The time schedule works out good where you can leave Denver early in the AM, check out the scenery, arrive in Glenwood Springs around 3p, walk across the street to the Glenwood Hot Spings Hotel, hit the hot springs and stay the evening.. and then catch the train back around noon the next day. But be forewarned.. rock slides do delay the train frequently
IMHO Amtrak space-wise is like 1st class, but delays can drive you nuts. I wouldn't want to be on there for more than 1 day at a time.
DT