What to Change?

So I've been thinking about last Sunday - wondering what steps to take for next year.  Obviously a lot can change - but it's worth thinking about it while the last experience is fresh in my mind.  

What happened last week?  My legs gave out really.  I probably ran 8:40s for the last 8 miles - losing almost a minute/mile from my goal pace.  The pain was localized in the 'hip flexor' area: quads, groin and (oddly) abdomen.  If that area did not break down - I would have been very close to 3:25, certainly under 3:30.

There are a few ways I can try and avoid this next time.  Acute - work on leg strength.  More global - run a lot more miles.  Plan tweek - increase the pace from the last plan.  In the end the first one may just not be enough, the second one i'm not willing to commit to and the third one may actually make things worse.  I think the most assured way to qualify would be simply running a lot more - but I don't want to sacrifice cross-training and realize that if I do 5 or 6 runs a week - i'd be lucky to do one good cross workout.  

I'm leaning toward a compromise of the three right now.  This would keep one strength session/week as before.  I would also have to be deligent about working the 'hip flexor' excercises 2-3x/week.  If that works well, then I'd be in pretty good shape with the FIRST plan.  However, I think I'm leaning toward a thursday run to bump up the mileage and hopefully make the Friday long run more challenging.  Finally, I would change the 'speed' and 'tempo' to look more like the hanson plan - but I would drop the MP to 7:30-7:40 - depending on what I'm capable of.  In the end - the will lengthen some of the Monday/Wednesday workouts.  I would also make the 'speed' work longer slower intervals (7:10s for 2 or 3 miles vs. 6:10s for 400m).  This should help the muscles not feel so worn going into the marathon.