My twins are ten and while they still have a few years before they hit teenage-status (Yikes!), I'm stocking up on books for teens, now. There are so many amazing Young Adult novels out there! I loved so many.
I definitely want to make sure they read some female-centered, female-hero books. I want them to have more than just their male perspective, so I think The Hunger Games trilogy will be a great place to start. I already have all of the Harry Potter collection, which they've already expressed interest in. I think they'll start those soon!