Steinbeck Center

If you have a chance to get to the Steinbeck Center, I strongly suggest it.  It's hard to imagine what a museum about an author might entail, but it really is spectacular.  I think you'll get the most out of it if you go after or while reading the book, because you'll be able to make more connections between the book and what you're seeing at the museum.
http://www.steinbeck.org/