JP2,
I can't do 'tried and tested' for you cos I'm training for my first marathon myself, but I thought I'd point you in the direction of the other 'sub-3:15' thread a bit further down the page, since this one is a bit more active with people's current discussions about training, etc. Come join!
For the record I'm following Hal Higdon's Intermediate II plan, but I've also started reading 'Advanced Marathoning' by Pfitzinger & Scott - highly recommended around these parts, lots of training schedules for different levels of mileage, etc.