We love to take the trip from Texas to Chicago (and back) via Amtrak (as long as we don’t get the Dining Car Nazi). We always get a sleeper for at least part of the trip, but also will go out and sit elsewhere on the train to stretch our legs. The sleepers come in various sizes so if you can spend the extra cash you can get a quite nice space. Even the smaller ones seem fairly sizable because of the big windows.
If you do get a sleeper, make friends with the sleeping car attendant. Many of them have great stories, and they can be very helpful.