ok, as for bigger = better. This moves off subject a bit, but it's the problem with the JLA comics. I was geting bored with it for 2 reasons. 1) it was starting to get incomprehensible. They'd do 5 or 6 issue story lines, and everything would just be getting worse and worse and worse until the last issue of the arc, when suddenly everything was taken care of. I can't figure out half of them. It was like reading Mary Worth with super powers in that we'd have several issues of just talking about how bad things are getting.
2) the universe can only self destruct so many times before you're thinking: Geez, just let it go. Start over.
the problem is you've got Superman AND Batman AND Wonder Woman AND Green Lantern AND Martian Manhunter AND the Flash (ok, and Aquaman), AND usually 5 other back ups, one of which is a frickin ANGEL. A real one. Like, from God n' stuff. Any ONE of them can throw down with a Greek/Norse/Hindu/Anything God. Put all twelve of them together and well, what can even be a remote challenge but the end of the universe? Answer: nothing, really. Lex Luthor even looks like a pansy except for the fact that he can get all the Superviillains together for a party and a good brawl (which usually doesn't end up a brawl anymore, disappointingly).
So I for one, don't think you have to go threaten the fabric of reality every time. It gets dull.
However, threaten the social structure, etc. It doesn't have to be a supernatural evil. WWII was a good example. You can do some epic stuff with that, and the Nazis don't have to be channelling Tiamat to be an overwhelming challenge (unless they're up against Superman, which, as has been shown in Whom Gods Destroy, they have to at least be challening various Greek mythological figures).
You can have an epic struggle just averting a war, like Nuclear war, because two nations misunderstood, a la Sum of All Fears. Localize it. As long as it means the end of the world for the community at hand, even a small village, I would think it's big enough. We don't care about the gits at the other side of the continent, so who cares that their lives will go on unchanged.
I still think new threats can develop without them having to be ancient. Maybe an alien race makes a startling breakthrough in tech that allows them to put smack down on anything, and you have to find the weakness.
Also, War of the Worlds showed us that the evil didn't have to be ancient to discover an Achilles Heal for it on our own planet/in our own locality. The Martians were a brand new threat Earth had no experience with, but just have one person discover that bio weapons would work, instead of having it be a pure accident, and voila, epic hero.
And at the risk of sounding generic, the corrupted person can be family (like Darth Vader) or a friend (like the first act of NWN).
I'll wait for reaction before I say more.
