I ride that route split road/ path. There's a stretch between Seagrove and Rosemary Beach where the road is only two lane, higher speed limit, and with little to no shoulders. Also lower density, so the path is a good option. Riding 20mph through Water Colors, Seaside and Seagrove on the path is next to impossible. Even if they're not clogged with slow traffic, cars pulling out of the beach condo complexes can't see you.
If you're a fool like me stop for some donuts at Thomas's (in Laguna Beach/Sunnyside?) Makes that ride back to Destin into the prevailing wind so much more fun.
If you want to find some rides with a good group while you're down there, see if you can hook up with the Emerald Coast Cycling Club. I did two nice rides off the coast with them last summer, one of 50mi, the other 57mi (two Saturday rides)