Garmin Coach for full marathon?

Couldn't have put it better myself.  If the Coach algorithms were better implemented and properly adapted to performance in sessions, maybe, but MUCH better to move on from them and use a heart rate based training plan with time runs rather than distance. The plans will automatically adapt to you then.  As you get fitter you'll have to work harder to get your get your HR into the right zone (as the zone will move upwards) and have to cover more ground in the allotted time (because you will be faster).  I did - and would never go back to a Coach plan now 

With a time predictor, find out the half marathon corresponding time for a half marathon and do the the half marathon training. It's works out pretty good.

Im going to run a Marathon i dec and need a coch

I highly recommend this book, which I used to train for my first marathon in April.  It's heart-rate based, 18 weeks long and I was blown away from the results.  It increased my fitness massively, I hit no wall (actually running the last 10 miles at an increasingly fast pace) and without injury.  My love of running has also increased hugely.  One running book that lives up to its reputation.  

+1 for a full marathon coaching plan

Please ....GARMIN COACH for Marathon!!!! 

Yes definitely 

Totally! I would love to have a marathon plan!

wow here we are screaming into the void four years and running

They're probably thinking: "Who runs marathons anyway!" lollllll