Is it possible to simulate the competition between the powers within each region? Could each superpower 'bid' for influence in a region, so that the one committing the most resources in a given turn bumps up it's influence one level? Depending on each power's level of influence, more options within that region would be available. I think there may be more choices than a large scale guerrilla uprising. Maybe this isn't what you're thinking or perhaps too complex, but it's a thought I had.