The two beaches I usually visit are Jekyll Island in Georgia and Mexico Beach in Florida. Jekyll has lots of rocks where the dunes ought to be as protection for their eroding north end. It does still have some smallish dunes on the south end. Mexico Beach trucks in tons and tons of sand to rebuild their dunes after each hurricane strike. This two plus story one feels like what a beach should be.
My favorite dunes are the gypsum ones at White Sands National Monument. We were encouraged to walk on the dunes. My second favorite was the Cumberland Island dune which was the biggest I’ve ever climbed.