The Enchanted Forest Chronicle: Boxed Set by Patricia C. Wrede

This is about a princess who's captured by a dragon, and then chooses to stay with the dragon rather than wait to get rescued by a prince. In fact when a prince comes to rescue her in the first book she turns him away, all of them. The series follows the pattern of a typical 'princess story' and the princess is put in a bunch of stereotypical princess situations, but then she defies the stereotype and takes charge of her own life and makes things happen for herself. Basically she beats up her own bad guys, with her brain. there are boys in the series, but she isn't waiting for them to save the day, she takes them along for the ride. The dragon who kidnapped her ends up being one of her good friends.
 
It's a fun series I really enjoyed in elementary school, but it an appropriate read for anyone interested in the plot (as are all stories... age ranges close your mind). A light fun read, I recommend.