for most people who can run a 1:35 half, then from your list, by far the easiest is the 3:30 full. You definitely have the base fitness to do that rn, you’d just have to change what you were doing for training.
In normal times the BQ is the second-easiest thing on there (3:20). Believe it or not you also might have that in your locker rn, you’re just missing specific marathon mileage / workouts / long runs, i.e. you’re at most ~six months away.
But apparently de facto BQ times are bananas right now—I don’t pay attention to this stuff so it might have calmed down but had heard that in some age brackets there was such a covid bottleneck that folks were having to go ten minutes faster than listed BQ time to actually get a slot.
The good news is that by the time your marathon time is safely BQ, then you’d be getting into the 7:20ish/mile marathon territory…and marathon paces like that are predictive of 5K times around 20 flat. (And btw if you’re getting a sub-20 5K then you’re getting your sub-6 mile, those two are a package deal.)
(and ofc as you know “predictive of 5K times blah blah” doesn’t mean you get the marathon and then roll out of bed and get the 5K too, it means that if you can run that marathon time, then given reasonable specific 5K training [like 12-20 weeks] you can probably run the 5K.)
In general the most efficient direction to do these things is long-to-short, meaning that in your spot more people will have better luck training for a 3:14:15.9 marathon and then going for the sub-20 minute 5K rather than doing the speedy stuff first and adding volume after. But YLMMV. And also as you get into your fifties and slip ever closer to unlimited nothingness then your window for the 5K stuff is probably closing first.
I don’t even like running very much. And I’m definitely not a marathon person. But I will say that boston was surprisingly wonderful and worth doing once. But there are fun 5K possibilities too, like if you get close to your goal then you can also take a weekend and go to a fast one like Carlsbad or whatever and run a great race and then that’s a thing you will have done
But mosdef is also right, in that it’s essentially impossible to consistently train for races for two or three years without having at least one obnoxious setback. And as you say, the whole idea of being an adult person with a family can be a clunky fit with deciding to go for some indulgent goal at competitive joggy joggy and for what, so that you miss your goal by eight or eighty seconds because of fifteen different reasons only seven of which you had control over, and then you get to look forward to feeling secretly miffed about this? How many millions of people who wanted their sub-whatever whatever and made a solid push three summers ago and finished seriously only eighty seconds short, and are still disgruntled because eighty seconds is basically sixty and ok it was also not fair because of the monsoon, or the stupid shin splints, or the safety pin on their racing bib that came loose and shiskabobbed their urethra that cost at least forty seconds, oh god if I had only had a fully functional urethra I could have run fifty seconds faster and then the other thirty and I wouldn’t have to spend the rest of my days with my own private thought-bubble smudge whenever people start talking about marathons because I wouldn’t have privately FAILED at some TOTALLY ARBITRARY dumbass thing that in truth wasn’t that simple because my wife was liking my shapely hindparts wait
3:44 is slow for you so you should probably do that. But if you want the boston stuff then your main thing is going to be mileage. Yes on low mileage it’s absolutely possible to get cute in a bunch of ways and save time and run decent races while living life decently. But eventually the thing everybody needs the most is more raw time spent running, period. There’s no way around it. And true for 5Ks too.
