(You can read the post I was responding to here)
As one of these newly emerging youth voters, and also am a huge fan of shows like The Daily Show and The Colbert Report, I'd like to expand a little about what you said when you said "The next generation is deadly serious about this country but they also manage to have fun with it. That's the Millennials' real message, it seems to me." It's something a little more serious than fun: it's humor. See, one of the cores of humor is perspective: in order for things like irony or sarcasm to work, the joke implicitly creates perspective towards the truth. If you can remember the terrible rip-snorting fun that was the 2006 Press Correspondent's Dinner with Stephen Colbert, you'll know that it was funny (or really not funny, depending on your perspective) precisely because of the truth that was imbedded in every joke.
I'd like to point out that both Barack Obama and John McCain were frequent guests on the Daily Show (McCain was at one point--and may still be--the most frequent guest of the Daily Show). They both share an ability to laugh at themselves, to poke fun, to show a little bit of perspective. As the campaign marched forward, I was afraid John McCain had lost it completely, but at that dinner recently he showed himself able to. And how did he appear at that dinner? A lot more in touch with the truth than he has been lately. Comedy requires that self-awareness that you and I both look for in a candidate, and it also means a candidate has to give up their self-importance a little in order to make a self-effacing joke. After all, Stephen Colbert's Press Correspondent's dinner was far more effective than if Jon Stewart had done it because Colbert made himself an image of mockery, and then included Bush and others into that mockery. Note that Nancy Pelosi has, on a couple occasions, warned Congressmen not to appear on the Colbert Report lest they get a mocking that they can't recover from.
I want a candidate who'll have a sense of humor. I mean, I wouldn't choose humor over healthcare, but at the same time, the ability to laugh and joke and break the ice, to see oneself clearly and have perspective on the world around us, to be able to burst self-importance and relax the walls a bit--that ability gives me a lot of faith in their ability to pass healthcare. And in this pompous age of ideology, vitriol, and hatred from both parties toward each other, maybe the future of both parties needs to have a lot more humor. Like Reagan deftly joking about his age, Bill Clinton's ability to connect with people (he hasn't seemed very funny lately, though). Even Nixon's memorable "Checkers" joke separated him from a pact of less worthy candidates. I'm not saying Nixon was a great candidate, but if you look at the way that Nixon and Mao were joking around together, you'll see why it was that it took Nixon to go to China.
Of course, in 2008, there is a limit to the sense of humor I'll take. As someone who wanted McCain to be a different candidate than he turned out to be, I feel pretty "punk'd."