I've been told that the very best book for identifying birds is the Sibley Guide to Birds. Opinions, anyone? Thank you."\
It is my favorite guide for identification and is used by many as "the reference" for North American birds. It is a bit big to carry into the field, so I also have Sibley's Field Guide to Western Birds which is smaller, lighter, & less expensive and if you will only be in the west, may be enough for you.
Speaking of "in the field," I no longer carry any books while actually birding, but use both the Sibley and iBirdPRO apps on my phone. However, those do not substitute for a quality reference at home or in the car.
Thank you for your response and advice. Much appreciated!
I'm with Bill on this, except insofar as I carry the pocket-sized Sibley Field Guide to Western Birds (I need the book a lot more than Bill, I suspect). I went so far as to buy cargo pants with an extra-big pocket for the book. :-)
Here's a suggestion: At the Rio Grande Nature Center, they've got a nice library of all the different guides in the viewing room overlooking the pond. Sit a spell in the room and try the different books out. Then they have most of 'em for sale in the little gift shop around the corner, so your money will help support the Friends of the Nature Center, too.