Jim,

The sleeping cars actually are a combination of both. On the side where the roomettes are, the hallway runs down the center of the car, with rooms on either side. The bedroom side has the hall running down one side of the car, with the room occupying the rest of the width of the car. You can view the car layout, as well as seeing where a specific rooms lands at Friends of Amtrak.

Now it is possible to book a specific room # if you like, via an agent either in person or on the phone. Booking online will not allow you to choose a specific room, even though the computer will assign one to you at the completion of the reservation.

However, since the car can be orientated in either direction, there is no way to guarentee that you've picked a room on the south side. Probably 60% to 70% of the time the car will be running with the bedrooms at the head end. That is the preferred orientation, but the cars can and do run with the roomettes at the head end. It's just the luck of the draw.