I've always liked the 10/10/10 approach from Central Park Track Club. More info here:
http://old.centralparktc.org/training/coach01.htm
You can tweak it all sorts of ways, but the basic idea is to split up the race into a conservative first 10 miles, a middle 10 miles at or below race pace, and a final 10k where you're either picking it up or trying to hang on.
I've run a 2:38 marathon splitting 61:10 for the first 10 miles, 60:15 for the second 10, and 37:10 for the last 10k. Within those sections I really worked to run even, and when I unintentionally split a 5:45 or something on mile 8, I made myself run a slow (6:20) next mile. Some people would argue that this is too conservative, and it's possible that you might be leaving 30-60 seconds out on the course. I would argue, though, that the tradeoff is worth it, because if you're well-trained under this plan you're almost certain not to blow up and run 10-15 minutes or more over your goal time. When you go out to fast over the first half, though, that's definitely in play.
Other things I like about this: it breaks up the monotony of the pace a bit; you aren't trying to grind out 16 or 18 miles in a row at the same pace. It's also nice psychologically because you're going to be passing a boatload of people over the last ten miles, especially at a big marathon. I'm not going to say you feel good at mile 25 or anything-- it's still a marathon. But you spend the majority of the time feeling like you are either running comfortably or attacking and very little feeling like you're hanging on for dear life.