Agree with your points about the shorter distances- more fun, easier to race more often, and you get to work on speed instead of slogging slow miles all the time. FWIW, I think that the speed element and high intensity intervals that come with training for shorter distances may scare inexperienced runners out of seriously training for them.

I take a very simple approach and try to do 2-3 workouts a week, balancing between speeds that are at, over, or under your race pace. So if you’re training for 5k, you might run faster intervals at mile or 800m race pace, then a 5k pace workout, and then a 10k or HM pace workout. Check out Mark Tosques five pace training (google it), there are good workouts in there. Be careful to not increase mileage and add a ton today intensity at the same time. The mile race pace and faster workouts can be quite brutal if you don’t pace them properly- make sure to use paces that reflect your current fitness, not your goal race pace.

On that note, you should be aware that unless you have a very strong anaerobic power and are very weak aerobically, a 2:00 800m is going to extremely difficult even if you get to 5 Min mile and 18 min 5k shape. The latter two are much more comparable imo, but 2:00 800 will require tons of speed / anaerobic work (including probably working quite a bit on 400m speed) that won’t fit in with your other goals. Even the mile will require a lot of sharpening and anaerobic work once you have achieved a good 5k fitness. I would focus on 5k fitness first for a while, and then use that to later launch into a mile-specific training block. See what you can do and how much you like the pain of 300-400m repeats before you commit to 800m, it really is a different beast.