The Pennsylvanian and Three Rivers used to rival the Auto Train, back when they were followed by a dozen or more express cars and Road Railers. Of course those days are long gone, but going around Horseshoe Curve and being able to look back and see all those cars was pretty cool. (It must be an amazing view to look backwards from the cab of a 100 car freight going around Horseshoe Curve, but I've never seen a photograph taken from that angle!)
The Builder is certainly impressive at 14 cars, but I'm still easily awed by the Crescent (anywhere from 9 to 11 cars). I know it's half the length of what it was forty years ago, but it's still impressive to me. Maybe it's the variety of car types. They don't match the way Superliners do, so it makes the train "more exciting" somehow, even though it's a little shorter.
(Yes, it must be the variety, come to think of it. I get similarly excited when I see SEPTA consists with a mixture of SIIs, SIIIs, and SIVs, or of ex-PRR and ex-RDG together
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