She's unafraid to mix it up (sometimes to a sartorial fault). She puts colors together that many people, some of my favorite people included, would say "don't go."
She likes the ease and flexibility of separates in daily life. (Those beautiful knee-length sheath dresses were for special occasions during the campaign.)
She feels young and is drawn to flirty shapes and flowery prints. (But she never overdoes it with the flowers — that would be an inexcusible offense.)
Here she is in Colorado and New Mexico yesterday in a cardigan, apparently ruffled top, and knee-length print skirt. (Mrs. O says she's wearing black trousers, but I think she's wearing the print skirt in the picture. Whatever.)
And I'd just like to add this: It's an extremely flattering look, one that works whether you're a little hippy or more narrow in the torso.