I was there last August. My FI and I along with my brother and his gf visted the Smith's family luau and Fern Grotto. Apparently it is a hot spot for weddings. As you arrive to the Fern Grotto the Smith family welcome you with some songs and entertainment on the boat. When I went there you were unable to walk into the fern grotto.. you can only see the grotto on a platform and unable to go into the cave. Back in the day people were able to go into the cave, I forget the story behind why it's closed off but no one is allowed in there anymore. On your way out you walk through a path of flowers and pretty cool looking plants! The luau and garden are spectacular. There are peacocks, pigs, chickens and other animals running loose but they won't bother you. You can also see a lot of their indigenous plants in the garden as well. I agree with the above post, you should definately do a private event because there are a lot of people at the luau. The food was good and the buffet line wasn't too long. I have a million pictures if you want to email me at firstname.lastname@example.org
I'll be happy to send them to you.