Amtrak Superliner Cars?

Depends on the car. For the dining car, the kitchen is downstairs. For the sleepers, there's roomettes, showers and a couple of large bedrooms. Coach/Baggage cars have the baggage section downstairs. Etc.

Amtrak chose this design due to the increased capacity per railcar. The design is based partialy on the Santa Fe/Budd bi-level cars.

Some coach cars have seats on the lower level and lavatories, also this is the Handicap seating. 

Quick google search came up with this:

http://www.craigmashburn.com/amtrakcardiagrams.html

Traveling by rail in these cars are actually really cool!

Here are some interior and exterior shots.