The thing is, I think you and tsq are preaching to the converted. Most of the guys on here would find a Sci-Fi/Comics/Fantasy costume a lot sexier than some non-existent outfit with a pair of wings attached. I know that's not what you are going for yourself, but that way you get to wear a costume that's not ridiculously revealing and looking good in it is a bonus.
I wouldn't worry too much about those types of girls if I were you. You're married to someone who loves and adores you, which means you've got the type of genuine attention and affection that those other girls haven't realized yet. I would think that being the object of someone's momentary desire is a pale substitute for what you have.
... At least that is how I hope I make my wife feel every day.
You guys are totally right. My husband saw the Bat-Girl costume and when I decided not to wear it to the party he said "... so you'll wear it at home?" with a huge hopeful grin on his face. Marrying a nerd was definitely a good choice.