I found this article interesting (link below) as President Obama gives a comparison of AA rating countries versus AAA, not a huge difference.
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A downgrade in America's credit rating is now a distinct possibility. That's true even if politicians in
Washington reach a deal to raise the nation's debt limit while curbing federal deficits.
Credit-rating firms are focusing not just on whether a deal gets done, but also on the uncertain outlook for the nation's future fiscal health. The debt plans currently under consideration don't rise to the level of the "grand bargain" needed to stabilize the national debt at an economically safe level.
But even if a rating downgrade occurs, that doesn't automatically mean financial catastrophe.
Consider the contrast between nations that have the strongest rating ("AAA") from
Standard & Poor's and nation's that are one notch down, at AA. Often it's hard to tell, from their interest rates, which is which.
http://www.csmonitor.com/Business/2...edit-rating-drops-Other-countries-offer-clues.