Jusr rode Amtrak 3 & 4 with my wife to and from Williams Jct. The ride in the Superliner sleeping cars seemed a little rough (lots of swaying and bouncing) from about 60 MPH up to maximum 79 MPH allowed on the line. The car attendant said that's how the ride always feels. Anyone have any insight on whether this is due to BNSF's track, or are the Superliner cars known for poor ride quality?