Should be v-e-r-y crowded the 4th since Navarre and west are still repairing. We were there pre-spring break and it was like summer with the crowds!
Have fun, though, and don't plan on travelling through Destin between 4:30 pm and 6:30 pm - traffic jams like you were NYC.
Bring a grill and buy fresh fish at Sexton's or , hmmm, forgot the name of the other place. Same side of street as Sexton's and in the general vicinity. Red and White building. Maybe called Destin Seafood? Anyway, grill fresh fish and don't fight the crowds.
restaurants - Back Porch, Fudpuckers, Louisianna L (long word), AJ's, Hogs Breath, Gratzi's. Many more that I can't think of