Get the memo: It’s cool to be quaint. Social graces are making a comeback thanks to etiquette divas like Martha Stewart and Miss Mannners. Thank goodness. Hosting fab little soirees in your own home shouldn’t be a lost art. Now we all can learn from the fairest hostess of them all—Jackie Kennedy. Or perhaps I should say Letitia Baldrige, Jackie’s White House social secretary. As Baldrige explains in her new book In the Kennedy Style: Magical Evenings in the Kennedy White House, her job included more than doling out doilies for Democrats. She orchestrated some sophisticated hoedowns, like the Nobel Laureate bash, the Pablo Casals gala, and a luncheon for Prince Rainier and Princess Grace. Baldrige and chef René Verdon recollect the swankiness, the grub, the Laureates signing one another’s programs. Sigh. Polish up on your social graces with Baldrige at 6 p.m. at the Ripley Center, 1100 Jefferson Dr. SW. $13. For reservations call (202) 2357-3030. (Gina Vivinetto)