Traindude,
You'll also be able to kill an hour or more having dinner in the dining car, and I personally would spend some time especially out of DC in the Sightseer lounge car. You can get some nice views of Harpers Ferry, an old canal that parallels the train route, and the climb into the mountains is rather scenic.
You can even send Stephen to the other end of the lounge car if you want some alone time. :lol:
You can certainly walk around the entire train, except for the crew car and the lower level of the dining car. As for sitting in the coaches, if they aren't sold out, then ask for permission first. I wouldn't be surprised though if they're sold out or close to it.
However, the lounge car is probably a nicer place to hang out anyhow, by comparison to the coaches.