Aedes de Venustas is a must for the ambience alone. They have decanted samples for me upon request. Beautiful decor and extremely helpful staff. I could spend hours at Aedes, and a fortune.
Barneys is good for the Malle scents and the limited release Lutens (Chergui, Fumerie Turque, etc.). You can also sample most if not all the Le Labo scents.