theres a diff. between staring and looking. its OK to look but if your sitting there just staring at her the whole time without trying to talk to her she may get creeped out. no one likes to be stared at but not talked to, its just weird.
have you seen the preview for that one movie "the adjustment bureau". the guy on the train is sitting right next to the girl. she happened to be wearing some sort of skirt or dress and she catches him looking at her legs. so he says "i was defenseless against a girl in a skirt/dress that looks so pretty in it". lol. just try to be funny about it they know ull look its how you act about it that they want to see
That morning, she chose to wear that skirt or dress and accepted the consequences in doing so. Girls aren't dumb, they know the perks that come with showing skin in public. That said, have the attitude that "if you're going to show me something, I'm gonna look". There's nothing wrong with that, and I'm sure that those girls have experienced much worse than a sheepish man's stare. You're not traumatizing anyone, so feel free to enjoy the best of both worlds!