First, it turns out that former Marvel Comics publisher, Shirrel Rhoades, lives down there, apparently moving down not long after he left Marvel. I discovered this because he had given an autographed copy of his book, Comic Books: How the Industry Works, to local restaurant, Sarabeth's. I don't recall seeing it come up in the usual comic circles, but it looked like a little bit more of an insider's view of the industry than most books. I'll be trying to pick up my own copy and review it here.
shown at the left was one of the more tame ones -- but only when seen from the front. (By the way, the gent in the somewhat more traditional Captain America outfit was with her, so their costumes were meant as a pair.) Not too many comic references overall, though. Besides Aquaman and the two Caps, I think I only saw one each Batman, Joker, Superman and Wonder Woman. For a week-long costume party that tends to have attendance in excess of 100,000 that strikes me as surprisingly light representation.
One of the local houses also decorated their place up with a Batman theme for, as far as I could tell, no discernible reason. Lots of places were decorated, but they generally tried to tie things to the aquatic theme. Why Batman? I don't know, but there it is.
There were some good costumes to be seen, and some which weren't spectacularly well-executed but still quite clever in concept. (The woman dressed as Maleficent from Sleeping Beauty had a particularly great twist on the costume that didn't involve showing any additional skin.) But overall, I think you could find better costumes at any decent sized comic con. And there's a much decreased chance of needing to un-see something at a comic convention, too!