One of the best writing books I've read lately is The Complete Guide to Writing Fiction and Non-Fiction and Getting it Published by Pat Kubis and Bob Howland.
The reason I liked it was that it approached the topics in a way that was understandable to me. The first chapter is Dynamics of Plot. It starts with the question "why Plot?" and breaks things down from there, explaining strong and weak plots, classic plots, plot structure, and the relationship of story to plot. Another important element for me was the introduction of the "W" diagram.
The "W" diagram breaks the action in a visual diagram that shows the rise and fall of the action as it relates to the protagonist. Examples are given from classic novels- I really liked this, because it irritates me to no end when writing books use MOVIES as examples. Other chapters are on Viewpoint, How to Open a Short Story or Novel, Three Dimensional Characters, Effective Dialogue, How to Develop a Good Style. Create Settings, Scene Summary Transition, Back and Forth in Time, Theme, and Do Titles Really Matter? I've pretty much ignored the Non-Fiction section of the book since I'm not interested in that right now.
My measurement of a good writing book is "Did I learn something I can apply to my writing"? In the case of this book, I've moved beyond the W diagram, but it was eye opening in realizing that there were other ways to plot. The other advantage to this book is that the authors give explanations of why they are stating something. WHY you want to have a strong opening, WHY characters need to be three dimensional.
At the end of each chapter is a series of exercises. I haven't done any. I used to be impatient with doing anything not related to my own writing, but after working through the exercises in a poetry book and getting some good solid poems from them, I am ready to revisit my snotty attitude and give the exercises a try.
Here is an example exercise from How to Open a Short Story or Novel:
Examine the second paragraph of Ernest Hemingway's hook from The Old Man and the Sea, the old man's description. Write down all the things you KNOW about the old man just from Hemingway's description. Analyze WHY you know these things. What particular things in the description evoke your reactions?
The book is a good tool on how to train yourself to read critically, for details, and how to develop great ideas for your own writing. There are some pages on query letters, submissions, and other things that may be of use sprinkled in the Non Fiction part of the book. I found this book in Barnes and Noble while trapped in Cheyenne for training one week. I haven't seen it anywhere else in stores, but Amazon and Powells have it. Worth checking out if you like an array of options to choose from. Otherwise, it may be too confusing for someone looking for more specific advice.