Jack Daniels
Over the years I have tried a number of training plans, and read even more. There are many good training plans available, especially for the marathon distance, but I have found Jack Daniels to be the best. Jack Daniels not only provides a series of plans for various distances, but also a way of calculating the correct pace for each workout. You can read more about this at VDOT. The book is well written, and Jack Daniels is one of the most respected coaches; Runner's World famously called him "The world's best running coach".
The second edition of the book adds in training plans for people just beginning to run and for first time marathon runners, as well as a plan for elite marathoners.
The biggest downside to the book is that is requires a little effort on the part of the runner. You need to look up your VDOT, then look up your training paces. The book does not give a simple, fixed weekly plan, but instead specifies the quality workouts you should do, and you decide what days you run them on. For marathon training, the book does not specify how much mileage to run, but gives a percentage of the maximum mileage you decide you can handle.
None of this is very difficult, but it does require some effort. Sadly, I think this has put some runners of the Jack Daniels plan to simpler, but less effective training plans.
You can tell how valuable this book is to me by the way my copy is falling apart. I use the book for some of my own training, but any time I create a plan for someone else, I base it around Jack Daniels.
http://www.amazon.com/Daniels-Running-Formula-2nd-Jack/dp/0736054928