Another vote for Sensational Knitted Socks! It is very easy to understand, and there are lots of stitch pattern options to choose from. I also love that the instructions are set up so that you can use whatever gauge you want. I just got Cat Bordhi's Socks Soar on 2 Circs for Xmas -- haven't tried it yet.
My one gripe with knitting books in general is that I wish they had bindings that allowed them to lay flat!