I love Shannon Hale's books. Even though books featuring boys sell better, Hale writes book after book with strong female leads. On top of that, her stories are great.
Book of a Thousand Days is another great book by Hale. Her other ones hook you from the start. Since the main character has been banished to a tower for seven years, the beginning of this one is pretty slow, BUT good things come to those who wait. Later on, the book gets just as exciting as her others, and I know you'll love it.
Have you read it?