Personally I prefer much more advanced books, I seriously doubt twilight is good for your brain (although I don't want to get into that discussion). But here are some of my favourite books, of which I have been reading lately:
-Little Bee (known as 'The Other Hand' in some continents)
-To Kill a Mockingbird
-Anne Frank's diary
If you're really looking for something girly and teenagy, I highly recommend Louise Rennisons book series "Angus Thongs and full frontal snogging" because it's the funniest **** I have ever read. She has recently started writing a new book series, the angus thongs one has 10 books. But they're all quite short and entertaining, and more for teenagers than for small kids. It includes quite a few sexual terms, but no worries, only in the funniest possible way.