I would have loved to see it in Prussia instead of the American revolution. Prussia has a strange history with many conflics which makes it the perfect place of an AC game to me. They had people all over the world and where very influential when it came to military matters. This culture hasn't been used before in AC games and fits in with the concept better the the American revolution. Other periods would be the French revolution, the Dutch revolution, and other major milestones in European and Middle-Eastern history.
I would have liked to have seen some ancient world powers like Persia.
Also the eighty years war is a real option, there is real prove of underground templar activity in the southern part of the Netherlands, and in that war several people were assassinated. The thirty years war could work, maybe the war of Spanish succesion. But the setting should fit. So maybe Amsterdam, wich was the most important city in the world during the Dutch golden age. Or Prague, Paris, London, maybe Königsberg. *probally spelled that wrong*