Good book suggestions!
I'm an "old school book learner" as well. But, as a serious "heads up", any "comprehensive" book covering Photoshop CS6 will be huge. I had to special-order one when I upgraded from CS2 to CS3, and it was huge, and seriously it was little-used.
Something to bear in mind is that much of Photoshop CSx is geared toward "graphics artists" rather than photographers, and for this reason much of Photoshop documentation is bloated and pretty useless for us photographers who don't want to do "fancy graphics".
Of course, the "users guides" would have Indexes (which I use) and the Help docs have Search, which I use. In fact, Photoshop Help (and Lightroom Help) are needed, to get a quick "how to" guide.
But I do value "primers" that are in fact oriented toward photographers, such as the Evening book that has been mentioned.
And then many people here have gotten a lot of good from the video "providers" of tutorials. Lynda.com is possibly the best -- they offer both a short "essentials" series and then tons of other tutorials. Another provider to look into is Scott Kelby and his KelbyTraining.com site. He also has a pretty comprehensive set of video tutorials authored by well-known experts.
As someone said, Photoshop books can, well, fill a lot of "library space". I don't grab books for PS willy-nilly. A quick glance up at 4 PHotoshop books sitting on a shelf above me includes a classic book "Layers" by Matt Kloskowski, another classic "Skin" by Lee Varis, dealing with portrait photography/processing, "Photoshop CS3 for Nature Photographers" by Ellen Anon and Tim Grey, and then a huge workbook/reference book from the NAPP Photoshop World Las Vegas conference -- it's from '07, but still chock full of goodies...
In other words, instead of grabbing a bunch of "comprehensive" Photoshop "manuals", I went for "specialized" books that focused on a particular field of Photography (although somewhere I have one of the Martin Evening "primers")...