Lonely Planet has a great deal going on right now. Buy any book and get the California Trips Guide for free through March 19th. Lonely Planet probably makes the most comprehensive traveler-centered guides I've ever used. I haven't checked out the California Trips book yet, but I've been thinking of buying the New England Trips book which features a Fall Foliage Tour, Literary New England and the White Mountains Loop. Now's the time!
Click here for more info on the deal.