He was an architect that just needed that extra help from someone. Part 1 was starting the clone wars to get a loyal army and a lot of power, by manipulating the senate. Part 2 was having anakin save him and allowing the galactic empire to exist for some time. Also, if Luke and Leia never existed, Anakin wouldn't have created the empire, because the only reason he saved Palps from windu was to get the power of the darkside to save padme who was pregnant with luke and leia. The galaxy would have been better if Luke and Leia were never born.