Thinking about it more, I think Artemis Fowl is especially good for gifted kids. He is clearly PG, but also clearly a flawed character -- he hasn't learned the lesson yet that just because he CAN do something doesn't mean that he SHOULD.
Agree with the Septimus Heap and Tamora Pierce recommendations as well. We met Tamora Pierce once at a book signing on Halloween night (my kids would not be kept away, even though it was Halloween!). So we went with them in their costumes, and then did some trick or treating afterwards in the neighborhood near the bookstore. D2 was about 7, and dressed as a hobbit. Tamora recognized the costume at once and complimented her, and D launched into one of the longer poems from Lord of the Rings. Tamora responded in Elvish. It was a great moment!
