Some stories stick with you, and the Enchanted Forest Chronicles, by Patricia C. Wrede, has been one of my favorite series for most of my life. I first read it in elementary school, and I’ve reread it every few years since then.
I love this series mainly because Cimorene (the main character in the first book, Dealing with Dragons, and a significant character in all the later books), is about the most badass princess you will ever meet. She’s not satisfied with the normal responsibilities of a princess, and when her parents force an engagement, she runs away, and offers her surfaces to a dragon. Dragons routinely take on (well, usually kidnap) princesses to take care of their houses, and Cimorene is perfectly fine with that idea. (She also bullied her household into teaching her to fence, cook, and work some magic, so she’s more prepared than your average princess)
Cimorene defies all the qualities typically given to princesses, but she does so without being necessarily critically about those qualities. She’s simply not that type of princess, even if such things simply aren’t done. Cimorene is unflappably practical, and her her strength comes mostly from her intelligence. She’s a wonderful role-model for children, without casting a bad light on other princesses; she’s strong, but not bitter.
All the books play with the concept of fairytales, so they’re entertaining to adults as well as children. They’re fast-paced and fun, but also pretty damn smart.