I liked 'My Father's Dragon' series by Ruth Stiles Gannet
Captain Underpants and Ricky Ricotta books by Dav Pilkey are a traditional favorite for making the transition.
He also read books the tied in with his favorite characters from TV and Games, such as Pokemon.
Sideways school books are funny and easy chapter books. Mrs. Pigglewiggle is more like a series of short stories.
I'd also try reading Harry Potter 1 aloud and see if he picks it up while you are busy without prompting. Try to act heart broken that he went ahead without you, ok? ((wink)) Then you can ask a lot of questions about what you missed.
It's a great idea to visit the school when they have their Scholastic book fair or browse them online. Developing a good relationship with the local Children's Librarian is recommended. Even Amazon's 'Other shoppers you looked at this book, enjoyed this book' can be a useful feature.
Smiles,
Grinity
