by Diana Wynne Jones
I read this one while in San Diego, too. I had been thinking about trying this author for a while, as Diane Duane, one of my other favorite authors had been compared to Jones.
Overall, this book was very interesting. I really identified with Sophie and I loved the fact that this book had magic, mystery, and a bit of romance, too. I highly recommend it to readers who love fantasy, and even readers who don't.