We visited in March 2014 with our 2 kids (3,11).
We were staying at Grotto Bay and the caves are a short walk from the hotel so was on my must see list. We toured both caves and all of us preferred the fantasy cave but I think a lot of that had to do with the guide we had (Ron) who was outstanding. Knowledgeable but also very entertaining.
The main cave was a great sight and the guide was good but not as good as the guide we had for fantasy.
There's other caves nearby that are also worth checking out...one at Grotto Bay resort and another at Blue Hole Hill park ( the blue hole one used to be a public exhibit as well).
Worth a visit and worth seeing both caves.