The Humphrey the Hamster series is one that is loved by both my daughter and my husband. Humphrey lives in room 26 and he helps out the families that he visits their homes and teaches kindness and friendship. For example, he unplugs a classmates television so the family can learn to have fun without the television. Humphrey's experiences make for good discussions of different problems that kids face, how to change these problems and how to help others.
This series works well as a read aloud (perfect in a classroom setting) and would be equally enjoyed by both boys and girls. The content is not age specific so it would be enjoyed and is appropriate for elementary students of any age. There are currently six books in the series and they're written on a 3-4th grade reading level.