KJ356: Fantastic photos. Most of what gets posted here are snapshots; those are photographs. Nice work.
IMHO the K-Line version of the Skytop is the best. It's the only one that is full scale size (except for the old Walthers kits, and some fantastically expensive 2-rail brass items). It has a full interior (unfortunately the car names are for sleepers and the interiors are parlor cars, but that's more a nuisance than a fatal error). The colors on the maroon and orange version are too dark. The K-Line car was made in both Hiawatha maroon and orange and UP yellow. It was also made in truncated 18" and 15" versions. The 18" came only in Hiawatha colors; the 15" was made in both color schemes. The MTH cars are undersized and the quality of detail varies. There have been many versions, some of which lack the chrome trim piece on the back, and some of which have paint jobs that never appeared on a Skytop. Lionel also made a Skytop, but that is a traditional size car - nice looking, but not in contention if we are talking about scale.
