Tangentially related:
The Blue Bird (St Louis - Chicago) had a dome coach car for a while and you could use that as your signature car. It was the Wabash which proved by experience that two cool-looking items - steam locomotives and dome cars - do NOT work well together (alas) - cinders from the locomotive fogged the view out of the dome.
This is not useful information to your inquiry but if you like the Wabash try to chase down the January 1966 issue of Model Railroader for an article called Modern Mixed Train Daily, about a spur off the Wabash main between KC and St. Louis, that went from Centralia to Columbia MO, GP-7 hauled freight and two passenger cars. Some interesting photos. That has been one of my all time favorite articles on MR over all these years
Dave Nelson