I haven't been to Luray Caverns since I was a teenager, but even back then I thought it was a cool place. That was the first time I learned what a stalactite and stalagmite were.
I don't remember much of the tour other than the formations and some colours, but I do remember that they had this "lucky egg" -- it was a part of one of the formations that kinda looked that an egg and if you rubbed it it was supposed to make a wish come true, or something like that. I guess they just wanted a gimmick.
I just went on their web site and read something about a stalacpipe organ, but I don't remember that -- guess my teenage mind just didn't care back then.