We love crystal palace also. Another great choice is Fresh at the Dolphin, it is fantastic.
Spoodles, not a buffet, but has an all you can eat entree.
Whispering Canyon also has that all you can eat skillet entree also.
One of the best breakfasts on property, not a buffet, but wonderful is
Kona Cafe. They have some giant platter breakfast...lol, it is huge. We love the calabash breakfast though.