How about the Napoleonic Wars on an international scale. Europe, North America and the Far East.
I would vote for the Cold War but I'd imagine it would be difficult to do. You would have to have the four superpowers USSR, USA, NATO & WP and then all of the other independant countries of the cold war such as Afghanistan, North & South Korea, North & South Vietnam, Cuba, China, Iran, Iraq. Not only that but you have to an 'industrial victory', an armeaggedon clock, amore aggressive UN and ideally a big red button. I don't think Civ IV is the right sort of game for a cold war.