Scenic Hwy 98 is a very popular 5 mile ride. It has a dedicated bike/pedestrian path on the north side of the roadway. This can be crowded during peak times so its good for a leisure cruise. There are numerous beach access areas and a large parking lot next to Pompano Joe’s Seafood House.

Staying on the 30A?

Here is the South Walton (County) 19 page Hiking and Biking Guide (14mb .pdf)
Walton County has over 200 miles of hiking and biking trails throughout its state forests and parks and along Hwy 30A. The area is also home to one of the largest Longleaf pine forests anywhere in the world. Walton County has 40% of its total acreage dedicated to preservation. People staying in the Destin and Fort Walton Beach areas will be amazed at how quick the scenery changes when heading east on Hwy 98 out of Destin.  Trails are paved and unpaved giving bicyclists of all types opportunities for trips along the beach or in the forest.