I think speaking is the key here. Like Bill Clinton who, for all his personal flaws, was a very good diplomat, I think that is what the US needs.
There is a grain of knowledge that Clinton had and Bush did not. Never, ever, turn something into a battle of wills. A Good diplomat understands that the other guys view is just as important to him as yours is to you, I always felt that was something Bush never understood. You cannot out-will another country, it'll never happen, the harder you try to force people to act as you wish, the more they will refuse to, hence the number of deadlocks around the world at this time.
America needs a diplomat, I'd say it desperately needs one, someone who can communicate not only with the US, but with the countries outside it as well. Right now, everyone is sabre rattling at everyone else, and their needs to be some common sense injected into the situation, it's already inflated itself far beyond it needed, simply because no-one would blink.
McCain, is probably the worst bet, in my opinion, because, after 8 years of Bush, voting in McCain would give a terrible message to the rest of the world, that America is happy with Presidents who are expansionist, centralist and confrontational, and, certainly in the more removed areas of the world, this will send a very loud message to the people there. They don't always understand how the voting system works, and will judge purely by the outcome, not the procedure.
On a side note, expect this election to be utterly rife with accusations of vote rigging...