We're going to Disney via the Auto Train! Although we've taken this train before, we've never had a sleeper before, so I have a question: We have the basic sleeping compartment (two seats that fold into one bed w/ one pop-out berth). It's my understanding that these compartments are on both the upper and lower level of the train. Which is better? A few years ago, we rode the upper level in coach seats and the rocking was a little tough at times. I'm guessing the bottom level has less rocking. Can anyone give me some advice? THANKS!