12 yo? I bet she could handle the Lion, the Witch and the Wardrobe. Or The Hobbit.
I second "The Hobbit" - totally wholesome and fun to read.
However, I'm not so sure about the Narnia books. I read them around that age and found the kids insipid and badly in need of having pranks pulled on them. For awhile, I actually rooted for the lion to eat one.