I am not over planning nor over thinking my trip to Guatemala. I bought myself these two books and that's it. The rest I'll figure out when I get there.
Frommer's Guatemala- Fabulous book with clear information that hits the spot. Nothing too heady or fussy. It's my kind of guide book.
Lonely Planet's Latin American Spanish - The only phrase book I need. It has the basics, is really wonderfully easy to read, is small enough to carry around and it has some of the most hilarious phrases in the romance section you can imagine. It's informative and damn funny!
I am taking the most important thing of all with me, of course. It keeps the fire lit and the good stuff flowing.