I have slept on several different trains - the Zephyr, Lakeshore LTD, Capitol, Pennsylvanian, in Coach, Business, Roomettes and Bedrooms. I am 6' 2", so trying to be comfortable is not always easy. Coach is miserable to try and sleep - and then the only way to TRULY get any sleep is if you're in a window seat. It's too bad they can't come up with lock-in-place headrests on the sides of the coach seats so you can at least put your head against one side or the other. If you're in an inside seat, forget it. You spend the entire time just trying to keep from either falling on the person in the window seat or falling into the aisle.
Business Class on the Pennsylvanian was VERY easy to fall asleep. In fact I was trying to stay awake and watch the scenery, but just couldn't do it. I have also always brought my own memory foam pillow with me on the trains, which really helps - especially that person who mentioned bedding - bring your own pillow!
I've been in both a Roomette and Bedroom on the Lakeshore. Viewliners are MUCH easier only because of the roominess - and having your own toilet is nice, too. The Bedroom on the Lakeshore was a little nicer just because I am a side sleeper and I liked the extra width.
I took the Zephyr from Chicago all the way to Emeryville this past Christmas. The first night I had a Roomette and it was my first time in a Superliner Roomette. The diagrams on the website mistakenly make the Superliner Roomette to be the same dimensions as the Viewliner and they're not even close. Even with the bunk above out of my way, trying to move around in the one foot by two foot space when the bed was down was near impossible and uncomfortable - but sleeping was wonderful! The bed seemed a bit roomier than the Viewliner, but I've always slept great in a Roomette or bedroom on the train. I fell asleep early - 7:30 and woke up around 3:30 or 4am, looked out the window at millions of stars above, barely hearing that constant horn, and the movement and train noises put me right back to sleep again. That's probably because my bedroom growing up was right next to the laundry room and the only time my mom could get any laundry done was when we got into bed. I still cannot fall asleep in complete silence and need some kind of white noise. The train is perfect. Plus having spent every Summer growing up at my grandparents in Kennewick, who had a 3 track train switch right next to the house, I quickly became VERY used to train horns and the beat of a train going by. The 2nd night on the Zephyr, I was upgraded to a bedroom and that was perfect. Great room and amazing sleep.
I would love to rig my bed so it could simulate an easy train movement along with the sounds. Man, I would sleep well!