Are you saying you don't want an enormous, privately funded school for children with powers?

If we want a post-apocalyptic wasteland, we could use the American Southwest, maybe with Texas to the East and California to the West as competing military-economic powers (and VERY different cultures/political makeups, which could be interesting).

If we wanted to get out of the States, we could look for a British Isles setting for a change, though I know Droo and Jace had designs on an Orwellian plot arc for the UK in Mutants, Unite. Alternately, we could land anywhere in a Balkanized Europe.

At the risk of cribbing Peter Jackson's style, South Africa also occurred to me. It could be near the epicenter of the event, and what world governments remain could have sent forces in to seal off the area and study it, trampling the locals in the process. Of course, of the three, that's the country I know the least.