We are using the "easy" version of the classics - though depends on what age and whether the parent finds the material appropriate. Good ones for boys so far have been: Robin Hood, Oliver Twist, Moby Dick, Dracula;

I've heard Diary of a Wimpy Kid is good for around 8-9 yrs old that like humor?

I would also look for easy versions of Count of MonteCristo and anything by Victor Hugo. No need to shy away from the classics!

The Green Book is also a neat story on Amazon - about a family that have to leave earth for a new planet.