We conduct 'Weekday Beach Minishoots' on Wednesday's during the summer here in SoCal, and if you're ever out here, you're welcome to attend. There's dozens of images on the MM port from those shoots... feel free to check'm out...
I shoot every week from Miami Beach to Jupiter Inlet, and I still believe the best beaches in the country are up in the Florida Panhandle. Best sand, cleanest waterline, nice wave action, and you can get as far away from your neighbors as you'd like. Ft. Pickens State Park in Pensacola Beach is a great place.
I'm originally from the keys, and lived there fairly recently. There are very few nice beachs (Bahia Honda is one) and it's a roll of the dice on how many onlookers/gawkers you're going to end up with.
Malibu has extraordinary beaches. You can get permits to shoot at them and it's not too expensive. I think shooting at the Keys would be nice. Southern California has a coastline that rocks--it has rocks, some gorgeous formations. Green cliffs, here and there. The colour of the sand on some of those beaches with the little caves just make it glorious. The movie industry moved here for a good reason.
Areas along the Gulf Coast of Florida is quite nice.. Siesta Key Beach has some of the best sand in the world.. All quartz so even when the weather is steamy, the sand is still nice and cool.. However, if you wants rocks and such, east coast of Florida is the best.. But tough to do sunsets on the east coast..
Now in the Keys, you have the best of both worlds being able to do both sunrise and sunset..