As far as real life interest, for me it is the:HEavyweight cars with the rear Open observation platform. Back in the 1990's I rode "The Blue Ridge" on many excursions out of Penn Station in NYC to Boston and Pittsburg. There's NOTHING like riding the platform at 100+ MPH down the NEC!
I also like Full Dome cars too [even though the PRR never had one...] But Conrail OCS was another story!
I also like the Amtrak's Superliner Lounge cars too!
"(did any northeastern roads?)" Yes the B&O did with thier capitol ltd.