I have. The NE is the worst because they have the ancient small passenger cars. Out west they have the cool double decker passenger cars.
As far as slow, I slept most of the way from CHC to NYC for a recent HOPE conference (which was across the street from the station, no $45 cab ride (or whatever it is) from the airport for me).
I find taking the train to be very pleasant, although I prefer the rolling stock west of the Mississippi.
