The best resource on Edward Weston is the "Big Book" as you call it. For those not familiar, the title is, "Edward Weston: Photographs from the Collection of the Center For Creative Photography," by Dr. Amy Conger. In addition to the thumbnail images of all the print holding in the center, Dr. Conger also wrote a very good biography, although not book-length by any measure. Plus with each image thumbnail Dr. Conger documents important facts about the photograph and how it relates to Edward's life.
Another excellent book is "Edward Weston: Forms of Passion." It has an excellent biography section of each period of Edward's career, and a critical analysis of his work. Included in the book are 320 duotone images from all periods of Edward's creative life. For many this might be the best book to own.
As someone who has read every book in print on Edward; studied under Cole Weston for several years to learned first-hand about his father; and having done original research with the Weston archive at the Center For Creative Photography, no one book or resource tells it all. The Edward Weston I have come to know evolved over several decades of study. I have come to appreciate more than the photographer. I have come to appreciate the man. He was an American original in every sense of the word. He lived a life few of us can fathom. And the man I have come to know, would have been a great man even if he never picked up a camera.
To answer a few other questions listed in this thread, Brett kept a Daybook for a very shot time in Mexico. Once he was introduced to the camera and photography he was a visual thinker and wrote very little. Even in the books he published of his work during his lifetime, Brett let the images tell the story, not words.
Charis' book on Edward, although a good one, and one I enjoyed immensely, only reflects on the period of his life they were together. So one doesn't get a complete picture of the man. Charis' book omits completely three important periods of his career. His world renowned work in pictorialism; his work in Mexico; and his post-Mexico period that yielded some of his strongest work: nudes, shells and vegetables. It is my observation that Edward could have quit photography in 1920, 1927 or 1930 and would still have been a giant in the history of photography.
And as for 50 years having passed since Edward's death, it is not too late for a biography to be written. The resources and information on Edward at the CCP have barely been tapped. The correspondence alone could yield untold stories and a new look at the life and work of this man. Plus with time comes perspective. I hope someone takes up the challenge.