anyone suggest a guidebook for the jmt( cali)

John Muir Trail: The Essential Guide to Hiking America's Most Famous Trail by Elizabeth Wenk & Kathy Morey

I looked and looked and could find no really good guide book. I see an opportunity...

I found the Wenk, Morey guidebook to be very helpful in the following ways:

Most helpful was the mileage and contour graphs at the start of each section. These I photocopied and carried with me. A look at when the trail was climbing or descending is nice to know for planning.
Campsites with their GPS locations were downloaded to my GPS. Although campsites were easy to find, at least twice having the coordinates was helpful. Letting me know I was near a good spot.
The mileage charts and campsite locations that are listed in chart form was very helpful in helping plan out my days hike. Although small, printed on the regular size pages, it has the maps.
The book has lots of detailed information about getting to and from the trail.
It describes side trips and hikes of the JMT.

The book describes the trail itself in detail, but this is not a guide to carry with you on your hike. It is a heavy paperback.
For example here is what I photocopied to carry. The start of each chapter has a small graph of the hike showing contours and where the campsites are along the line that represents the trail. Next to that is a list of the important junctions and mountain passes with elevations and the mileage between the points both total (cumulative) and in between points, plus the UTM coordinates I really like having this info with me.

I would definitely recommend this guide book.

A shorter guide is one written by Thomas Winnett and Kathy Morey. It weighs 7 oz. the Wenk, Morey weighs 14 oz.
The contour charts cover 100+ mile increments and is in less detail, but shows all the passes. This would not be as helpful because the lines are just srtaight lines that shows the rather obvious ups and downs of the passes. It does show mileage and elevations. The maps are printed a bit larger and more clear than the other guide. On just one page it has a list of Point Descriptions, N to S distances, distances between the points, and S to N distances. Then it has the trail descriptions with an Appendix of "how to" information. The pages are nicely referenced to the corresponding maps. The map sections are on separate pages. This, too, is a helpful guide one you might be tempted to carry with you, because it is smaller.

Another reason the Wenk, Morey guide is larger is that it has the chapters in order both for a North to South and for a South to North hike which makes it much easier to follow no matter which direction you are headed. If you like to carry trail descriptions with you, you could just tear out the pages you need. About 100 pages for each direction.

Another guide with glossy pages and pictures is one written by an Englishman who out lines how he spent 21 days hiking the trail. Each day has a map and descriptions with pictures of his day's hike. A Cicerone Guide by Alan Castle, entitled The JMT.

Another guide is entitled JMT, Day and Section Hikes, by Kathleen Dodge. It has maps and descriptions as the title suggests.

I would not recommend the Starr Guide to the JMT and High Sierra Region. It has lots of details, but is a bit dated even in its format.

There are other guides for Mountaineers who want to climb the peaks and guides with routes for off-trail hiking trail.

As you hike along this beautiful trail realize that all of the jagged peaks around you have been climbed!