Absolutely love my Sibley's. It is also available in Western and Eastern versions for a smaller haul. The behavior guide is fascinating.
Go by your local birders' store if you have one, like a Wild Birds Unlimited. Those folks will know the best guide for your area. We have the "Birds of Oregon" guides from both Adventure Publications and Lone Pine Publishing which give larger territorial maps of our state while Sibley's maps are of the nation. These books have the added advantage of being more packable.
Waiting for the Lewis' Woodpeckers to arrive. If I want to make the WBU folks faces go green with envy, I tell them that we actually have Lewis' come to the feeder. Niener-niener. 
Oh, I forgot. Before you go, do some googling for a birder's checklist for your area (or get one from the store). Those are invaluable when you're trying to figure out which one of a million birds you saw. Otherwise, you can do a lot of recordings of LBJs and LGJs.
Last edited by SadieKate; 04-08-2009 at 07:53 AM.
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.