I like, a previous poster on this thread, am a long-distance kind of guy who is trying to work on their 800m as much as possible. I certainly don't have the power (anaerobic capacity and basic speed) to run a fast 800.
I always try and apply the rule of specificity as much as I can. Which means I prefer the idea of plyos, hills, and circuits to improve my weakest link. I think weights could be useful, just to spice things up a bit once in a while, but you're MUCH better off the other way.
But there is an issue with guys like me who are trying to move down (the reason we are long-distance guys in the first place), and it's that we lack those explosive FT fibers needed to burn a fast 800. So, keeping that in mind, would it make sense to HYPERTROPHY those few FT fibers in your LOWER body by doing some weight workouts (you still do hills/plyos)? And once you reach that optimum weight (say you gain 5 pounds) you shift your focus completely towards hills/plyos/circuits?