A Summer Reading List for My Kids

My 9 and 12-year-old sons are pretty good readers. I do let them pick what they'd like to read (Rick Riordan's Percy Jackson series and Suzanne Collins's Gregor books are favorites), but I also sometimes introduce books to them that they might not immediately pick up. Example: one of my favorites, A WRINKLE IN TIME by Madeleine L'Engle. My oldest balked at it after reading the first chapter, but I encouraged him to stay with it, and now it is one of his favorites.

I'm putting together a summer reading list for my sons–books that I want to encourage them to try. What are some of your favorites for the 9-12 range?