Stinky's Fish Camp - They have private area upstairs or you can rent out the Bait Shack. Amazing food and fun atmosphere on the lake with dock across from the beach.
Redfish Taco - they have great food, outdoor area, and privacy inside or outside can be arranged. They can cater to whatever food you want.
Ovide at Hotel Effie in Sandestin is a beautiful space with brunch and music.
Same for Havana at The Pearl in Rosemary Beach and Fish Out of Water at WaterColor Inn.
The Bay restaurant has a private room, and a beach and dock on the bay. Same for North Beach Social across the street by same owner.
Local Catch and Chanticleer are both good options by same owner.
Bud & Alley's is always a popular option and they can set you up private if you like. Or just take over the rooftop.
Details
A directory of all South Walton 30A Restaurants with details, menus, photos, maps
sowal.com