On the other hand, it's certainly true that the Athenians supported the Ionian Greek cities during the Ionian Revolt, and that is seen by many historians as the proximate cause of the first Persian invasion.
Given that almost all of our evidence about the Persian empire comes from Greek or other Western sources (e.g. the Bible), it's really hard to know very much about their internal arrangements with respect to tolerance and the latitude subjects had to do as they pleased. Certainly, they treated the Jews better than had their predecessor empires.
As much as I admire aspects of Athens in the Age of Pericles, and as despicable as aspects of Spartan culture appear to have been (again, our sources are mostly Athenian or writers who settled in Athens), I don't think either polis was particularly good example. A point which our Roman forebearers understood well as they crafted a Republic with elements of both, while rejecting some of the worst aspects of both Sparta and Athens.
Though the vogue in the past century or so has been to praise the Greeks to the detriment of the Romans, I have long been and remain of the view that the Roman Republic was in many respects a far greater achievement in the ordering of human affairs than any Greek polis.
The Delian League only became as such AFTER the war with Persia was won and Pericles/Athens got the idea that the Delian League should not end with the war over but become a tributary to a new Athenian empire.
Athens let the power of an overseas empire get to her and it corrupted her democracy. That is the real uneasy lesson of history.
Yet the Roman Republic became an autocracy did it not?
Also, the Roman Republic was modeled after Greek examples well known at the time but now forgotten in favor of the Athenian version. Rhodes was seen by Aristotle as being the ideal constitutional republic of the Greek world and Rome emulated that example - proportional representation, etc.
If we see Rome as just another Greek city state then we can both agree because Rome was a non Greek people who became Greek in all but name and language - and even then many Romans spoke Greek better than they did their native tongue.
Rome did finally stop Greeks from killing each other though. Till Rome more Greeks died at the hands of their fellow countrymen than any did by invasion from outside. Through Rome the Greeks met Isocrates' vision of uniting as one people - the first Greek to ever call on Greeks to unite into what we would now call a nation. Alexander tried and failed.