For an excellent bird field guide, I highly recommend the American Bird Conservancy's Field Guide, "
All the Birds of North America," by Jack L. Griggs -- it has a plasticized cover and, in my mind, the best indexing and illustration as well as range info and field marks explanations. It's perfect for use in the field. I have the previous edition, with the dark red cover.
The illustrations really are what make this book for me -- they show the birds in their various plumage variations and posing in ways one would actually see them in the wild (not just every bird in the same position, or worse, numerous varied quality photographs where it's hard to tell if differences you're seeing are due to lighting or due to actual differences in plumage.)
I have several other bird identification books, but "All the Birds..." is the one that comes with us on coastal birding trips, any camping trip, etc.
For "leave at home" bird identification books, my favorite is
The Sibley Guide to Birds by David Allen Sibley. They just came out with Eastern and Western U.S. editions of this book, which I presume are smaller and might be useful in the field. Problem is -- Texas tends to get a mixture of both Eastern & Western species, as well as tropical migrants.