In terms of branding I think the 20th Century Limited has it beat as the most successful service ever offered by a U.S. railroad, at least in the heyday prior to the jet age. The red carpet, celebrity passengers, the featuring of the train itself in movies, the moniker of the "Most Famous Train in the World," I could go on and on. Let's face it, if not for the general collapse of long distance rail ridership it would likely still be operating and still be the "Most Famous Train in the World" today! As far as Amtrak goes, in terms of branding I would say Acela is their most successful.