Thanks for all the wonderful advice.
We had a GREAT time! Unfortunately it dipped down to the 50's one night (on Long Island in August) and we were unprepared for the cold spell. Two blankets were left behind on the couch and we only had 2 with us. I didn't bring sweatshirts either because I thought we wouldn't need them. No big deal. We were cold but not frozen.
We only went for 2 nights which was perfect for our first outing. We're already planning to go next year!