To answer my own question...
Attack Ye Old Crayoned Castle with a giant dragon:
Turn all your stuffed animals into superheroes, complete with capes made from Daddy's old ties. And underpants, of course.
Pull your favorite animal books off the shelf to look through.
Teach Daddy a new card game with the Star Wars cards.
Teach Daddy how to play LIFE: Pirates of the Caribbean edition.
I am so grateful that my boys get along really well, even after days of Not Much Going On, and that they are able to create their own fun, even when Mommy isn't much help. Even when the baby is cranky, the older two are patient with him and try not to take it personally. They are such good examples for me. :)