books for my nieces

I've got two nieces, 10 and 13, both read a lot. The last time I saw them, I gave the 13-year-old A Natural History of Dragons. Turns out she *loves* dragons, so I lucked out there. The book she was reading was The Life of Pi. I gave the 10-year-old The True Meaning of Smekday, which I was worried might be a little young for her, but I love that book so much I wanted to share it, and it turns out that like most avid readers, she enjoys things intended for older and younger people.

So I'm casting my mind around for Christmas presents. I haven't read Uprooted, but it seems very popular among my reading list. Maybe Seraphina, but a kid who loves dragons has probably read it already. The Cloud Roads wouldn't be too mature for a kid who chose to read Life of Pi, right?

Do you have any suggestions?