Dave, I've often wondered about that. So, if I am in a standard oceanview, and enough pax above me leave their balcony doors open at night, could my AC be affected? (I've heard lots of answers on this one, but yours is the one I'll trust.
As far as what I wished I had brought on my first cruise -- a journal! I started keeping them several years ago, and it's great to look back. Unfortunately, I do not have any from my first five or so cruises.