The Musée des Arts Décoratifs has an impressive permanent collection of furniture, fashion, toys, wallpaper, tapestries, glassware and other art objects from the Middle Ages up to modern times, including Art Nouveau and Art Deco. Special exhibits are always well curated. Best of all, even though it's just around the corner from the Louvre, it is far from the maddening crowds, so you can enjoy the riches at your leisure.
Musée Des Arts Décoratifs, Rue de Rivoli, Paris, France