The thing is, Mary Poppins is rather lipstick and nylons herself, not as a frivolous thing, but as trappings of propriety. She's aware of how pretty she is and of her femininity, but at the same time she is very buttoned-down. And for all the magical things she does, in the end she ends up pretending they never happened. "Jumping into a chalk picture? How preposterous!" Much like another awesome magical woman we know! I'm not so clear what they have to offer each other, but they have a lot of similarities. I'm intrigued by the idea of Susan and Mary's adventures in Narnia though! Singing faunish songs and dancing dryad dances and acting like it never happened, except for a shared knowing smile.