I always find older boys a bit more challenging to keep busy, especially difficult if you only have the one! I allow some electronic time ( I have an iPad that I allow the kids to use), I have some more complicated crafts ( more 3D building kind of stuff. I was surprised how much my older boys liked learning how to make pom moms with yarn!
I have a large collection of books, including some comic or graphic novels. They really like the non fiction books about weird facts/tales, amazing animals, Guinness book of records, etc. I have some puzzle games for one person (like Rubik cube and Tetris)
And of course getting outside as much as possible to the park where they can usually find another boy to kick a ball around!