I'd love to see a Cold War Scenario myself, maybe called "The Long Twilight Struggle", with the goal being to "take over" as much of the world as possible without going to war with any of the major Civs. So maybe you can play as China, Arabia, America, France, West Germany, Japan or Russia (the major Civs), with all the other modern civilizations represented as City-States (though you might have some other major Civs, like Persia or Egypt, so as to have a good spread of major civs across the board).
Another thought might be to change religion & Social Policies for the purpose of the DLC. Have religion elements replaced with Ideologies (Communism, Fundamentalism, Liberalism, Fascism), but which can be spread & utilized like religions in the base game. Social Policies might be more trimmed down than in the base game, though in what way I'm not sure.
Aussie.