A couple more suggestions.

My daughter loves Dick King Smith - "The School Mouse", "Babe the Gallant Pig", "Aristotle" etc etc...Many of them have lots of pictures some are more traditional chapter books.

We also love Kate Dicamillio. "Mercy Watson" is a newer series of picture books. She also has longer chapter books. "Because of Winn Dixie", "The Mysterious Journey of Edward Tulane" etc.