unrestricted observation car at Glenwood Springs, Colorado

An end-of-train flat car with seats but without roof or windows - obviously placed as far from the steam loco belching soot and cinders as possible - about to head eastwards in the Colorado River canyon on the Denver and Rio Grande.  This very scenic experience is still to be had on the Amtrak California Zephyr, but you will get enclosed air conditioned observation cars, albeit with curved windows between walls and roof to give a good view, as well as seats that can swivel.