The candidates also dealt with matters of greater substance, including foreign policy, taxes, Social Security and gun control.
They voiced general agreement on most of those topics, as they have done throughout the race, with both expressing confidence that they could proceed with a relatively rapid withdrawal of U.S. troops from Iraq no matter what the circumstances on the ground there.
Obama and Clinton also disputed the recent assertion of presumptive Republican nominee John McCain that both Democrats would raise taxes on all Americans, saying their plans were limited to revoking the Bush tax cuts for individuals making more than $250,000.
Obama, who seemed on the defensive for much of the conversation about personal vulnerabilities, said that such topics - including the fact that he rarely wears an American flag lapel pin - distract people from dealing with the more pressing matters of economics, health care and foreign policy.
"I have never said that I don't wear flag pins or refuse to wear flag pins," he said in response to a voter's videotaped question. "This is the kind of manufactured issue that our politics has become obsessed with."
Clinton, asked whether she thought Obama could defeat McCain in the general election, replied at first: "We're going to have a Democratic president. It's either going to be Barack or me." Pressed again, she said: "Yes, yes, yes."
She also said jokingly that she had hoped the Republicans would be so ashamed of their performance over the last eight years that they wouldn't run any candidate this time.
But that wasn't going to happen, she said, describing McCain as a formidable opponent and herself as a more electable opponent for him.
"I have a lot of baggage," she conceded, "and everybody has rummaged through it for years."
While much of the debate at the National Constitution Center covered familiar ground, one unlikely and relatively new topic did emerge, involving the long-defunct Weather Underground.
