I didn't see an Roald Dahl mentioned. The Witches should meet all of the criteria. Also I just got my daughter the Chronicles of Ancient Darkness which get rave reviews. The MistMantle Chronicles also look great. He could also read the Spiderwick series but they aren't very long. How about - Mrs. Frisby and The Rats of Nimh. My kids and DH loved it and were but a small warning there is no sequel and everyone was sad that it had to end.