I'll take you up on this. I (still) believe that the American social system still retains some significant differentiators from other societies. One can easily point to recent events that tend to undercut this argument, but I think we can still brag about a few things. I would point to three factors that may be important:

We do retain some shadow at least of the Enlightenment foundation of our system. Our constitution is better than most, and is stable. Everybody here buys into it (except for the part about guns) and there is no serious move afoot to make significant changes.

Also, our modern internal revolution was one of the early ones, and while there are still a lot of hard feelings, the issue (slavery) has been resolved. At least, it's been resolved in most legal senses, although obviously there is still plenty of racism in play. I would argue that the situation here is not worse than anywhere else, though.

And our society is homogeneous. This is bad from the viewpoint of "Walmart in every town" and "everybody eats at McDonalds" but it means that we have 300 million people who have absolutely unrestricted (by law as well as by societal norm) ability to move from point to point. I think this plays an important part in providing social stability, because there is virtually no difference, outside of the weather and the cost of a house, between Chicago and Baton Rouge. You can live in either place and be happy or unhappy as it pleases you. I don't think this situation applies anywhere else in the world.

There is just not that much disagreement about how things should be run. Example: If Bush and McCain are so horribly out of touch, why are the presidential polls so close? Because the policies of McCain and Obama are not hugely different. Example: Why were the "protests" at the Democratic convention in Denver, which were highly publicized in advance, such washouts? Because people are generally happy with the system.

The U.S. may collapse at some point, but I don't see it happening any time soon.