My family (2 adults, 4 kids ages 4-12) did the "Walk Back in Time" in July '10. The route was well-chosen with interesting sites and the guide was very knowledgeable; it was a good way to explore the Smokies and their history, and I'm glad we did it. That said, since I found out about it through the terrific reviews on TripAdvisor, I want to let people know where this service lost a star with me.
I had emailed well in advance to ask if a 4-year-old would be okay to do this walk. I was told kids this age do these walks often and that it should be fine. However, on the day of the hike, our guide-- who was good in every other way-- paid no attention to the fact that we had a small child with us, and moved at such a pace that my husband had to carry our son on his shoulders most of the way so we could have any chance of keeping up. There were only three families on our hike (all with kids, of which our 4yo was the youngest), so it wouldn't have been that big a deal to slow down just a bit. When she stopped to talk about a site or plant, she never waited for us to catch up, so we usually missed the beginning of whatever she was saying. It made me unhappy to feel excluded from a hike we'd paid for. I felt like my husband and our son were treated like third-wheel tag-alongs, and that put a real damper on our experience.
Also, although we had 6 people in our party, we were given the same amount of the "snack provided" as the 4-person families. This would mean one small cracker and a few peanuts for each person, so I skipped my part of the snack so my kids could have a bit more. It was another thing that sent the message that our "extra people" were off the radar (even though they were paid for). I might not have noticed this small issue if it hadn't been for the fact that I felt sorry for my husband and kid for being ignored.
I would do this activity again, but definitely not with a child under age 7. The guide was very good and knew a great deal, but despite what I was told, it was made clear to me that there is a "keep up or get out" approach to these hikes. On the way back down the mountain, there were numerous times when all the kids (not just mine) were trying to stop to see a very interesting bug, or a pile of rusted equipment just off the trail (still have no idea what that was), or a butterfly sitting on a rock, and the guide just kept going without ever turning around, so we all had to rush the kids away from what we were looking at to follow her. I understand if she was working on a tight schedule, but it's something to keep in mind if you sign up for one of these hikes. If you want to move at the pace of your own children, you're probably better off walking this same trail on your own.
Wish I could give a better review, but that's my experience, sorry to say.