BIRTHDAY SUITS: The extra men came from all over for American transplant Lee Radziwill’s 70th birthday party in Paris on Monday night. Decorator Nicky Haslam, producer Doug Cramer, “Steel Magnolias” author Robert Harling and bon vivant Taki Theodoracopulos joined local walkers Gilles Dufour and Claude Roland at a dinner given by New York publicist Hamilton South. The get-together, at society hangout Le Voltaire, began with cocktails in the restaurant’s informal brasserie room and continued with salade de haricots verts and roast chicken in the two main dining rooms. Radziwill favored U.S. Ambassador Howard Leach and Cramer with the seats of honor on either side of her. Afterward, she blew out the candles on a cake decorated with a mini Eiffel Tower, in honor of her latest residence. Parisian buddies Mathilde d’Agostinelli (who gave Radziwill an intimate dinner at home the night before), Jacqueline de Ribes, Betty Catroux, Inès Sastre, Leslie Caron and Victoire de Castellane came to pay their respects, as did Radziwill’s trainer and three concierges from the Plaza Athénée.