We took the train from Philadelphia. I don't recall the particular name of the type of room we had, but, it was smaller than I expected. I'll make an attempt to describe it to you, it was narrow length wise and short height wise. There were two seats facing each other and on the right of one seat was a small sink with a mirror and little waste basket. On the train in Philly, there was a little TV playing three movies and if you wanted, you could turn it off. And of course, between the two seats was a large window. There is leg room, but not that much. We also discovered a small storage area overhead, but it didn't have a door to close over it. At night, the two seats are transformed into a bed and another is lowered from the ceiling. The only problem with that was that the speaker for the TV was right at the head of the overhead sleeper. Once in "bed mode" prepare for little or no space to move around, so you will most likely have to dress lying down. But then, while you're eating breakfast, your attendant will put everything back for you, and if he doesn't you can just ask and wait for about 5 minutes, not to bad. As for fitting in the room, you have to remember that there will be a lounge car to sit around in and you won't be spending ALL of your time in the room. At night time, I would say two adults in the lower bunk could be a tight squeeze, but the overhead bunk is out of the question, trying to fit two adults in that or one kid and an adult is just uncomfortable to think about

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We also had 19 stops during our trip down there, this is what I thought was going to be terrible, but in fact, it was barely noticable, and another bonus is that you could sit and take in as much as you could as you wait for the train to start up again.
You might want to check out the AutoTrain too, even though it departs in Lorton, VA, it's worth it because you have your car with you and can get bigger accomodations. It's just a matter of willingness to take that trek down there.
I know it's a lot, but I hope you helps you decide, have fun!