^^^^^^ Didn't read the 2nd page posts... haha. I see you corrected yourself.
Anyway... At some point you have to stop trying to appeal to someone and just be yourself... In this case that's what I suggest. The times that it's most important to appeal to a crowd is if you're doing an entire set somewhere... Since you're just doing one song just pick the one that comes most natural to you. I'm pretty positive that any guy in the crowd is going to like watching you play and sing either way. Something magnetic about a girl with a guitar. Bit just do what feels right for you. Most guys that I know don't like Ryan Cabrera........ but that doesn't meant that they won't like your rendition of his song....
For times like these it's good to know some songs by girls like Alanis Morissette and Sheryl Crow... Those are song good song writers... And a new girl on the scene KT Tunstall... "Suddenly I See" and "Black Horse and the Cherry Tree" are both killer tunes and not too hard to play.