Great points have been made thus far and just from the aspect of a busted up runner I would say that racing marathons is as much a privilege as a right.

By that I mean nothing is guaranteed, so yes theoretically you could run SF as a fun run but what is to say you will recover physically and mentally in time to want to train for CIM?  I personally came to loathe running when training for two marathons in a season but there are those who excel at it, obviously.

CIM is on my short list of events to run and if you train properly and go into it at the top of your game the course allows for a complete destruction of your current PB.  That is a big fat juicy carrot hanging out there and I am not sure I could turn that down.

A pretty good case has been made for how you could do them both so you have a choice, but if you are already dreading an 18 mile run I think your mind & body might be making the case for why you should not.

Think about it, for most of us the start of marathon training is a time for excitement and enthusiasm.  If either of those two elements is lacking the road ahead may be a tough one to hoe.

If you did decide to do it I would go with a 12 week plan for CIM just to give yourself a break, but good luck with whatever you decide.  I hope a 5k is in there somewhere too! 

I don't know if I have any helpful advice, but I will say that I have almost *never* felt really good and enthusiastic about running when I've started coming up on the 18s and 20-milers in any plan.  It's a tough point because your legs have had so much running already, but the taper still seems so far away.  I think your plan is a good one (to just run by feel for now).  Maybe running SF and doing the 12-week Pfitz plan is the way to go-- maybe scrapping SF and doing the 18-week Pfitz plan is the way to go.  I think you'll have a better idea what you're up for closer to the date of the race.  I've never run a marathon 'for fun' so I'm not sure how much it would take out of you to do it.  I do find that after a hard marathon effort, the mental recovery is more important even than the physical recovery... After one hard effort I can't even think about putting in any amount of hard training for at least a couple of weeks.

Or, you know, what LRB says.

I had trouble training for a March marathon and a November marathon, last year and I think those were further apart than SF and CIM.  Eventually I got it together in time to train well and PR for my early November marathon, but I had many weeks of 'ugh, whatever' running-- nothing longer than 6 miles and nothing more intense than an easy fartlek.  I think basically all of April and May of last year was 'ugh, whatever' runs, and I'm not sure I really got it together until July.  The March marathon was a hard effort, though.

I have never quite figured out why everyone thinks the Pfitz plans are so difficult.  Daniels is hella harder.

It's all relative.  Compared to a Higdon beginner plan, Pfitz was a beast.

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My heart says to run SF, but my head says to go with Option 1.  Also, can a marathon really be just a "fun run"? I  fear I will either be depressed to have a worse time than I did last year, or push to beat that time, which will jeopardize my training for CIM.

 

Sorry this is so rambling.  Would appreciate any thoughts.

Sure, people do it all the time. 20 marathons, including one as a dress rehearsal. I was coming off a serious injury and finally able to train again but it had been 5 years since my last marathon, which was a total bomb. On top of that I was dealing with a mysterious cramping issue with my hamstrings. If I didn't get that sorted out the BQ attempt in the Fall would be suspect. So I purposely chose a hilly marathon to test supplements, new shoes and just to get the feel of a marathon again. The BQ attempt in the Fall was something I'd focused on for 5 years and I just wanted to get my feet wet again to boost my confidence. I had zero time goals and treated it as a supported long run.

No formal training schedule, just a few long runs. Ended up getting everything I wanted out of it. No hamstring hickups, felt very comfortable the entire way while finishing 9 minutes short of my qualifying standard. Not performing any specific training for this race gave me no option but to treat it as a glorified long run. It's not something I'd ever do again, but it fit my unique circumstances perfectly. I ended up qualifying in the Fall, running 14 minutes faster.

Given your opening comments it sounds like you need a break - mentally and physically. I'd go with Option 1.

I think this is my real concern -- can I content myself to run a marathon knowing it will far from my best effort. If I can't, why am I training for it.

For me the dress rehearsal meant nothing. The BQ attempt in the Fall meant everything, so even for someone that loathes the idea of giving less than 100% in competition I had no difficulty in treating it as an experiment for my Fall campaign. The amount of time I invested in my goal made the process easier to manage.

One more point. I used to love the training that was involved with preparing for marathons - fall asleep thinking about the next day's long run. I trained with passion and I believe the results illustrate that. When I stopped feeling this way I either quit all together or shifted my focus to other distances. My last marathon was in 2010 and I have zero [0] desire to train for or race another. Will this change? That depends on what my body can handle and what my heart tells me. The thought of a 4 hour marathon isn't appealing to me. I do enough jogging in training why would I want to do that with a race number? Jogging is not something I particurally enjoy, it's something I must tolorate in order to compete.