My son-in-law proposed to our daughter 2 years ago just down the beach from the Soggy Dollar. We knew it was going to happen on our charter trip, just didn't know when. Before that, we were sitting at Anegada and there was a double rainbow. We all thought he'd pop the question then - ha ha! But he waited till JVD, took her on a walk down the beach and on their way back got down on one knee. :-)
Our advice to him: don't do it over the water!! That rings goes in the water and it's not going to be the moment you though it was.
I think Cow Wreck would be a beautiful place.
If you head inland for dinner, the view from the top of Bananakeet restaurant at sunset would be beautiful.