Hello, Pentex...My one and only train trip was several yearswhen I traveled from New Orelans to Chicago, which was about a 22 hour ride.
I rode coach. The Train ride was OK...some gentle swaying, but OK , but the train was obviouly an old one, as some of the seats had more wear and tear on them than I expected ( duct tape covering holes in the seats !)
This was is August, and the A/C was so high, it was freezing on the train...good thing I brought a little cover up...but the whole train may have been that cold...I don't know as I only went from the dining car to my seat, or the bathroom.
If you can sleep easily in a reclining position, then you might get a decent nights sleep, but I had a hard time and only dozed, which meant that I was really tired when I arrived in Chicago the next afternoon.
Just my personal experience...other things happened too, but not because I was in coach...just in general, like the train stopping for two unscheduled hours in some small farming town at 3am, with no explanation as to why, and on the trip home, would you believe that the train"ran out of water" ! and Amtrack made no effort to stop to get some, so no water to drink or wash up or to use the bathroom.