I've written before about how much I love this series of mythology biographies. They are so good that you should read them all right now if you haven't already, and also, buy copies for all the kids you know, who will also love them. If you don't know any kids, make sure the local library has them.
One of the great things about them is that in the extensive back matter O'Connor explains his choices and decisions as to which stories to include and how. Great stuff.