While I still believe that Practical Paleo and The Paleo Solution are essential core reading, over time one comes to realize that if you've been eating according to the "Food Guides"... you likely have an autoimmune condition that would benefit from following this protocol for a period of time before following the general Paleo protocol.
My wife was the first to read through these books, and you can see her reasons and what she learned in one of our autoimmune posts.
Sarah Ballantyne is the author of our new autoimmune books and has more information on her Paleo Mom website.