The last time I was at the Roanoke transportation museum, it was a little dead. It did have one of the big engines they used to build and run, but it was a non-runner just sitting there. In this link they show some of them they had sitting there, they are monsters.
http://www.vmt.org/collections/rail/
I do not know if you are up to this, it would take the whole day. I really enjoyed the Cass Scenic railway. I rode on the Cass classic Bald Knob run. I see it's rather expensive now at $61 per person. But we left the station about noon, and did not get back till around 5pm. That is a steep railway, it even has a switchback you have to go through to make it up the mountain. They have to stop along the way and add water to the engine. And that engine really struggles sometimes pulling up that hill, it's a pretty good ride as far as train rides go. They push you up the hill so you do not get all the cinders falling on you the way up. You can take a little something to eat, they stay up at the top for a little bit, and make sure you take a light jacket no matter how warm it is at the bottom when you start out.
I did the google map thing, it said from the campground to Roanoke is about 2 hours. That is mostly interstate 81. They showed Cass being 2 hours and 35 minutes. And it's a very curvy winding road, you are pretty much going over to the middle of nowhere. On the way you will see a huge satellite dish they use at the radio astronomy place, it's a quiet zone over there, no one has cellphones because there are no cell towers over there.
Roanoke is way cheaper than the Cass ride, but I had a lot more fun at Cass, if you guys are into to old train rides.