It's been a long time since I've been there. Those tours seem short - more like half a day rather than a full day. I don't remember there being much to do topside, but like I said it's been 10-15 years since I've been there. There are other, non national-parks caves all over down there, so you could probably find others to visit. Mammoth cave is the best that I've ever been in.
I think we did the historic cave tour, which was pretty neat. They talked about how the native americans used the cave and such. We did the Grand Avenue tour as well, but I don't remember the other tours we did.
I was actually thinking about going back for some of the Wild cave tours, but I'm too big. I read something that said you wear a size 42 or larger sportcoat you'll be too big to fit certain places, and I wear a 48, so that's not happening. My shoulders are broad enough that I'd probably get stuck.