Rose Cleveland. (She doesn’t seem to have made the list, but she did the First Lady bit before her brother made his Gilbert & Sullivan marriage to his ward.) Because she was an intellectual, an educator and editor, and her book George Eliot’s Poetry and Other Studies, contains some nice philosophical thoughts about manners. 

Edith Wilson. Because she managed to run the country fairly discreetly (everybody guessed, but they couldn’t pin it on her) when her husband was too ill.

Lady Bird Johnson. Because of her version of the adoring-wife-next-to-podium look, which clearly telegraphed, "Shut up, Lyndon, you’re making a fool of yourself," and brought him to a sometimes abrupt, but always speedy, conclusion.