I just completed a cross-country Amtrak sleeper-car journey from New York City to Spokane and flew back from there. (I would have continued to Seattle or Portland but everything seemed to be kind of on fire).

I got off in Chicago for few days, then rented a can in Montana and drove around for a few days before getting back on.

The Lake Sore Limited line had much better sleepers with windows on the top bunk. The Empire Builder has that amazing viewing car though with panoramic views.

Until I got to Glacier National Park the first leg between NYC and Buffalo was much more beautiful. Glacier is not worth trying to describe, just go see it.