Reply to "18" or 21" passenger cars"

I Started off with MTH 18” semi scale passengers cars.

Once I got my hands on my first full scale passenger car there was no going back. I did an O72 layout expansion just to accommodate them. I hide many of the turns in the tunnels.

Full scale CN dome car, made by Golden gate depot. Solid brass and only a handful ever made

Lionel 21” NS excursion cars. 100% awesome. I installed Kaydee  couplers and decorated interior (see below)

decorated interior of a Lionel 21” passenger car

Atlas O full scale MBTA Comet II passenger cars. Made over a decade ago, but still awesome by any standard