My favorite Walthers cars are the 9122/23 series. These are coaches, and they come with windows paired or not, and clerestory or turtle roofs. For my purposes, they approximate PRR Cars I used to see in the 1960s on the Main Line, and seem to come almost close enough to the SP Harriman cars to please me. I do have PSC Harriman cars, and if I were going to be picky, I would say that PSC got it right. But they sure sound tinny rolling around the test loop.
Anyway, here are a couple Walthers coaches.