Sounds like a conversation I had many times with my mom and friends.
I remember calling my Mom my sophomore year of college and asking if she'd be attracted to me if she were a guy my age. She said, "No". She said guys my age want the Bud Light models, not a smart, studious girl who's ambitious. It didn't help because I saw all the other girls getting the guys I found attractive.
I wish I understood the psychology of the teenage boy - or any man for that. So much is driven by what other people think of them, what girls they think will be easier and those that don't threaten their status.
Perhaps the AP classes don't expose her to the guys she's interested in - that happened to me as well. Not that they would have necessarily been interested in me, but it didn't help that I didn't have those classes or those friends in common. Even being a cheerleader and a gymnast, I never fit into the "popular" clique in school and had a hard time finding my place.
She sounds perfect - I hope she has the self-esteem not to let not being the object of their desires pull her down.
I'd almost recommend letting her see all the people you went to high school with on Facebook and what they've made of themselves vs. where you are in your life. A lot of those popular guys are overweight, still partying like they're in college and the typical cliche of the popular guy in high school many years later.