I don't tend to run Supers games. I think it's because besides Elfquest (another world I have difficulty coming up with decent plots for) I cut my reading teeth on X-men comics, and I can't help but spoof them.
See, your traditional superhero comic has a lot of things that I just don't really integrate into my gaming. There's a lot of property damage, even if there's not a lot of "Pow!" and "Bang!" happening. My meihem tends to be subtler, if a bit harder to get out of the carpet. There's usually an antagonist with epic plans over small grievances. My games tend to have small plans with epic consequences.
Putting together a Katie Karnage game really takes from a formula that I haven't quite written down, but would look something like this:
1) What wacky plan does this Shadow of Brand want to accomplish?
2) How did his minions get it wrong?
3) How does this affect Katie's sales figures, so she has a motivation to stop them?
With those three questions answered, everything else kind of gets improvised for plot purposes. It's all a matter of stalling tactics, wherein I create a location for the plot (usually has a quirk or two of its own) and a wacky NPC or two with some useful information, but usually just has a hook to Katie.
Tell me that that's not how traditional superhero comics work. I mean, really.