I have Understanding Wood. If you're interested in the science of trees and how it affects the wood you work with it is an interesting book. Besides how to cope with moisture in the wood, it also discusses wood movement and strength as well as the best ways to machine, join, finish and stabilize wood. It has lots of pictures, formulas and charts. If you like to read textbook style books, you can learn a lot from Mr. Hoadley. I have the 1980 edition, I'm not sure if the book has been updated since then or not. It also has a chapter on wood identification.
I don't have any joinery books (there's plenty of magazine articles on the subject), but I do have finishing books. I have Understanding Wood Finishing by Bob Flexner and The Woodfinishing Book by Michael Dresdner. Both do a good job of explaining the difference between finishes, how they cure, selecting the best finish for the job and how to apply them. Bob's book also gives directions on how to get certain looks (toned cherry with rubbed lacquer for example). Either one should help you understand more about finishing.
Tom.