I'll vote for the Thirty Years War also!!!!
It will be a difficult project to simulate the whole war but if someone can pull it they'll get instant recognition from the grognards.
All the different phases, Danish intervention, Swedish intervention and the final French intervention. More or less in the story: the English Civil war and the Dutch war of independence.
Muskets and pikes, shock cavalry (yeaa the Finns!!!), sieges and fortresses, defecting and unreliable allies, Richelieus' money to keep the war going.
Some great & famous generals: Gustav II Adolf, Baner, Tott, Horn, the Great Conde, Turenne, Gallas, Pappenheim, Tilly and Wallenstein.
Never been done so what's not there to like? (Ok, I'm a little biased

)