They say presidents grow in office. You could say the same thing about their spouses. Michelle Obama certainly has the TV talk show rhythm down.

On Monday’s “Tonight Show,” Jay Leno — with the first lady just returned from representing the United States at the London Olympics and star gymnast Gabby Douglas on deck — flashed a photo (no doubt White House-approved) of Obama as a little girl posing on a backyard swing set. He noted the absence of an actual  swing on the bare metal frame.

That was “in the hood,” the first lady said, without missing a beat. “We worked with what we had.” She was smiling as she described running outside to play, making the best of it and being grateful for that. It was funny, and got the audience laughing, but it was poignant, too. She didn’t need to point out the obvious, how far this little girl from Chicago had come in her all-American story. (Leno did spell it out, asking Obama if she thought, looking at the picture, “No way that little girl is going to be the first lady of the United States.”)

Obama’s West Coast trip had included stopping at singer Gwen Stefani’s home for a fundraiser, and the first lady did slip in some politicking Monday night, naming health reform as something the administration is most proud of, with everyone, including those with pre-existing conditions, able to get insurance.

But the “Tonight Show” appearance was more an “I’m just like you” moment, as the audience in the studio and at home got to listen in on a chat with a beautiful woman in a summer dress who just happens to live in the White House. Her down-to-earth appeal was reinforced by a retelling, with video, of the “kiss cam” story, daughter Malia egging on the first couple for a giant-sized smooch at a U.S. men’s basketball game. “She orchestrated that second try,” Michelle Obama said of her older daughter.

And there were shots of the fit first lady at the London Olympics, being lifted by an American woman wrestler and cavorting with children at a “day of play” that had her ducking under a cover and temporarily out of sight of the Secret Service. “Sometimes they don’t know what to do with me,” she said, managing to sound respectful and mischievous.

The first lady turned the table on Leno with her own prepared “bit,” caught on camera moments of the host sneaking pizza, fries and doughnuts after he had promised to switch to healthier choices in her last visit to the show.

Wives are an important part of this campaign. As a comedian, Leno in his monologue lamented the lack of material with all the family men on the parties’ tickets, not a Herman Cain or John Edwards in the bunch., he said. On Sunday, it was Ann Romney‘s turn to shine at a Mooresville, N.C., event. Taking a cue from the tough tone of the GOP campaign, she said of and to the crowd, “They’re here because they get it.” Everyone loved it, though she may have to temper the confidence so it doesn’t sound like arrogance. (Will the people who don’t “get it” be forgotten in a Romney administration?)

It took Michelle Obama awhile to hit her stride, too. Now that she’s an advocate without losing her warmth, she’s become one of team Obama’s biggest assets. Campaigning is “a privilege,” she said to Leno. “The divisiveness you see in the news doesn’t exist out there.” She had kind words for the public and the media for not breaching personal boundaries. They’ve “looked after our girls.” When asked about the GOP candidates and their families, she said, “We welcome them to the campaign.”

At the Olympics in London, Michelle Obama remembered her father, physically disabled and in rapt amazement as he watched the games on TV with his family. On Monday night, she talked about the Olympics being a time when children, families and communities come together. Her next challenge is guest-editing iVillage, a Web site for women, focusing on back-to-school issues.

When Gabby Douglas came onstage on Monday, toting gold medals almost as big as she is, the first lady slid over, and there was the sight of two African-American pioneers, just chilling. Douglas got encouragement and a little mock chiding from the first lady when she revealed her first post-gold medal indulgence: an Egg McMuffin. And she showed she may have been taking media lessons from Obama when Leno asked her to judge the form in another childhood photo, this with the future first lady standing on her head. Douglas didn’t hesitate before holding up both hands to give her a solid “10.”

Mary C. Curtis, an award-winning multimedia journalist in Charlotte, N.C., has worked at The New York Times, Charlotte Observer and as national correspondent for Politics Daily. Follow her on Twitter: @mcurtisnc3