Barack Obama in Philadelphia on March 18, 2008: A More Perfect Union (embedded). Watch the entire 37-minute speech. You won't regret it.
You are right on the money. Most people whom I've seen link to this speech comment on how it doesn't have any catchphrases or short clips followed by loud applause that can be played for 30-second news round-ups. This is not a media-grabbing speech by any stretch of the imagination. I can't say if that's a good thing or not in general, but it definitely grabbed me. It chew me up and spit me out with a renewed appreciation of somebody who can spot problems in the world and describe them with clarity and meaning instead of short, content-less slogans.
BTW, after saying "'Nuff said," I realized that's the wrong thing to say, because it closes the door on what was said. Instead, I should have left it open to debate. I guess I'm still trying to achieve that perfect union with myself...