I've ridden in coach overnight on the California Zephyr 3 times now.
I'm only in coach for about 12 hours overnight.
The Capitol Limited is scheduled to do CHI to WAS in just 19 hours.
My experiences in coach have been good enough that next month I'll spend 2 nights in coach, 1 night in a sleeper, and then 2 more nights in coach on a 5 night train trip in a big loop Chicago - LA - San Antonio - St. Louis - Chicago. 4 trains.
The Capitol Limited uses Bi-level Superliner cars.
Each Superliner coach car has 5 restrooms on the lower level.
One of the 5 is spacious enough for people in a wheel chair.
One has 2 sinks and a toilet with a door and is known as the Ladies Lounge.
One is a restroom/changing room.
The Capitol Limited also has a Sightseer Lounge (SSL) car between the coach cars and dining car.
The upper level has big windows and lots of seats. The lower level has tables and the Café.
https://upload.wikimedia.org/wikipedia/commons/5/5b/Amtrak_Superliner_II_Sightseer_Lounge_Car_-_Coast_Starlight.JPG
Coach seats recline a fair amount and have a lower portion that we can swing up to support our legs. Plus there is a foot rest attached to the seat in front of you.
Superliner coach seats have a 50" pitch, way more legroom than the 32" average seat pitch airplanes provide.
Many people have little trouble sleeping. It's a good idea to have a travel pillow and blanket with you.
Some of those that do have trouble sleeping go and sleep in the SSL car, either on one of the 3 seat.angled, couches or on the floor between the seats and the outer wall.
If I stay at my seat to sleep I sleep fitfully but am sufficiently rested the next day regardless.
Many of the people in the SSL car start conversations with fellow travelers they have met for the first time.
There is more comradery on a train than there is on airplanes.