I recently finished a road trip across the country. This book came in handy every step of the way, from making reservations for lodgings to finding places to eat once we got there.
Understand that this book doesn't have eveything. There's not enough space in one book for too much detail on any one place. And it primarily (with some exceptions) covers only the largest cities in each state.
But it's a great way to get started planning a trip. I made many of my best lodging and eating choices of my trip based on this book.