If you are handicapped, prepare to be pushy. Chicago was the only terminal that was set up to make things easy for all travelers. Some trains also have 1st class, where the seats are bigger and coffee and tea are free. I didn't find this to be any great bargain. Some sleeping cars have showers.
Some trains are double deck, where all but handicapped sit in the top tier.
If you have trouble with stairs, the double deckers are not fun, because the snack bar and the bathrooms are all on the first level. Some are single deck. Since these train cars are reversible and the bathrooms are only at one end, you could end up in a situation where the closest one is 2 full car lengths away, so choose your seat carefully. Also consider which end of the car you will be departing from, as you must have your stuff ready to get off the train when it stops. If you have several pieces of luggage, you won't have time to make more than one trip.