Okay, I've decided. If I ever get around to kicking off this campaign, I'll use Icons. Much as I love Marvel SAGA, I think this is one that I and everyone else will grok faster. It has other benefits, like being easy to get ahold of, too. (I was wrong about the PDF before. That was an older edition. Here's the current PDF version.) It almost feels like a modernized version of the old SAGA game, anyway.
Like I said before, I'm leaning towards the Beta City setting. No firm decisions on that point, though.
Even if there's no campaign, I'll probably use this to run some superhero stories at conventions. I'm thinking I've finally found the system I need to bring the Micronauts to life, for one thing. Had been thinking Vortex, but, while I'm sure I could make that work too, Micronauts was always closer to super-hero than sci-fi.