For New Orleans, there is a whole FT thread of restaurant suggestions here. But I would do the traditional things like beignets at Cafe Du Monde, lunch at Commander's Palace, fried chicken at Dooky Chase or Willa Mae's. Brunch at Court of Two Sisters.

In the Destin/Ft Walton area, great seafood at Harbor Docks https://www.harbordocks.com/, great views and food at Back Porch, theBackPorch

If you go to Atlanta, I am a fan of the Wrecking Bar Brew Pub, https://www.wreckingbarbrewpub.com/ . Ponce City Market, in an old Sears and Robuck building. Top floor has great views and their is a walking path, a la the NYC highline you can stroll.

Charleston has a ton of great restaurants. We had a great brunch at Prohibition last year and dinner at Poogan's Porch. While it is a chain, Another Broken Egg has amazing breakfasts. Pearlz Oyster bar has some great seafood. And there are famous restaurants, albeit pricey, like Husk (right next to Poogan's Porch). And there is a Husk in Nashville and Savannah.