Check this on a detailed map
I-85 to Montgomery, I-65 (toward Mobile) to Georgianna,AL
Left on AL-55 toward Andulusia, right on 29 toward Brewton,AL
Left on AL 137, becomes FL 189 (old logging road, stright south)
Left on US-90, RT on FL 85 toward Niceville (you can also take shortcut just after cement bridge to right and skip Crestview, but that's real insider stuff)
Left on FL-20 to Mid Bay Bridge Road/Drive (cross beautiful bay)
Right at light into Destin