Yes, the Nazi parallel is the most overt one, but there's also Rome and the British Empire, though who knows how many were intended by George Lucas.
There's some parallels between the Clone Wars and the United States Civil War as well. While the slavery and state's rights issues are the most well known divisions between the two factions there was also Southern discontent over tariffs in the period as well since the nature of the Southern economy at the time meant they paid a much higher percentage of tariffs then the north.
And both Lincoln and Palpatine used powers their position normally didn't have in the interests of national security though in Palpatine's case he arranged for laws to be passed granting him those powers while Lincoln just did what he wanted and ignored court rulings telling him that he didn't have that authority until about halfway through the war Congress passed a law oking what he had been doing for years at that point.