I also agree that Jiko and Boma are both 'not to be missed', but another option is the Gaylord Palms. From AKL head east on the Osceola Parkway, past Pop Century (which will be on your left) and Wide World of Sports (on your right). GP is on the right, just past the intersection with the I-4.
We've eaten at all three restaurants and wouldn't hesitate to return to any of them.
Sunset Sam's Fish Camp (seafood

) is partly set on the sailboat in the Key West section of the hotel. We ate there for lunch, but from what others say, dinner is better.
Villa de Flora is a mediterannean themed buffet (breakfast, lunch, dinner) in 'St Augustine'. We've only eaten lunch here, but it's very good as buffets go.
We love the Old Hickory Steakhouse (Everglades section) and ate there for the third time a couple of weeks ago. Both the setting and the food are outstanding, but it isn't cheap.
The Gaylord Palms is worth a visit, even if you don't want to eat there. It's a 5 minute drive from AKL. Check it out
here.