With the exception of Sweet Tomatoes, I have never been overly impressed with any of the buffet restaurants. Some were OK, but Sweet Tomatoes (IMHO of course) is the best of the bunch.
You might try Joes Crab Shack. Not a buffet, but several people have said it was good. Bonus is that there is a playground outside.
As long as there are no nut allergies, Logan's Roadhouse (again not a buffet) is a neat place to go. There are buckets of peanuts around that you shell and deposit the shells on the floor. My kids love it there (DD was last there age 3.5)
Another one of my kids loves is the Kobe Japanese Restaurant. They cook the food in front of you on a hot plate. A meal and entertainment in one. (it kept my DD who was 18months at the time entertained).
Hope that helps,
--Kay