Amelia Island group lunch
Buster, I've spent a fair bit of time on Amelia Island, and it's a pretty small place, with lots of cozy restaurants, but I can't think of much for that many people. You might want to try PLAE at the Plantation...I've never been there, so I don't know how big it is, but they may be used to big parties staying at the Plantation. If you're willing to go super casual, B.A. Pig (excellent bbq) might be able to take that many, or might be able to cater it.