In modern times it seems that when a government is overthrown, even if that government was a brutal dictatorship, what results is often far worse. Iraq, Libya, Egypt, etc. have all pretty much been disasters, Syria is shaping up to be one as well, and I'm sure there's plenty of other examples in Africa, Asia, and Latin America that I don't know too much about. Taking out the current regime seems to always create massive destabilization, and a power vacuum that is usually filled by someone much worse.
Why then did the American Revolution seem to work out so well? It was definitely a somewhat bumpy road getting the constitution written and the government established, but it was by no means chaos. With the British gone there was plenty of opportunity for some rogue group with the less than noble intentions to take over and send everything to shit. Why did everyone then seem to pretty much just follow the Founding Fathers?
Is it that these modern examples of revolution are usually perpetrated by a small group that's not representative of the general public? Is it that they're usually strongly influenced by outside forces (cough the united states cough) that rarely have the good of the actual country where the government is being overthrown as a top priority? Is it something else entirely, or a combination of a bunch of factors?
I would put a lot into the fact that Washington devoted his life to being a better person and leader, and was pretty universally respected by the political leaders both during and following the revolution. We lucked into someone that literally took becoming a better person and leader as his first and foremost duty.
And the revolution in a way did not work at first - the Articles of Confederation were a failure that pleased no one. But the Constitution managed to resolve or postpone many of the initial complaints, put the country on a solid financial footing by assuming war debts from the state's, and led to Washington as the first President. It helped that he created a multipartisan cabinet.
Also, the US had the advantage of a very gradual process of centralization, going from an impotent National government under the Articles, to a slowly more influential and powerful government over time.