Children's Hospital Boston takes really good care of families. They set up the Center for Families as a home base for a lot of useful resources.
The Center has games, toys, books and movies to borrow if you're staying overnight. (It works just like a library. You'll even get your very own library card to use while you're here!) They've got computers in the Center, too.
The staff can give you lots of great information about the city of Boston, like where to stay and things to do while you're here. They can also help your parents with any questions they may have about the hospital.