Cantina Laredo is at Grand Boulevard in Sandestin, and, as much as it pains me to agree with Happy2Bme, they do make a great margarita, and their food is great too. One of my favorite restaurants.
I pretty much stick with Los Rancheros BUT if Red Bar reopens, they have the most delicious and most deadly margaritas ever. More than one requires ShallowsNole to get a ride home and sit on the front porch and sweat it off. Be sure to eat something first.