"Gallery" cars? With single upper-level seats on either side, and a railing to keep you from falling into the open center? Caltrain in Northern California still runs some of them, but for many years, they've been switching over to more modern bilevel commuter cars.
Amtrak also runs two distinct (but mutually compatible) kinds of double-deck cars. Superliners have the main level (and the end doors to pass between cars) on top, and a lower level with restrooms, carry-on racks, and accessible seating, and are used for long-distance trains where tunnel clearances permit; they were modeled after cars built for the 1956 version of the Santa Fe's "El Capitan." "California cars" are similar, but designed for shorter runs, like the Surfliners, the San Joaquins, and the Capitol Corridor; they're like Superliners, only with more Spartan seating, bigger stairwells, fewer restrooms, and twice as many doors (all power-driven, whereas the doors on Superliners are manually operated).