Bringing new meaning to "open bar" Double A (108 W. Kinzie St., lower level; 312-329-2444), the exclusive 65-seat lounge that launched downstairs from Mercadito last Thursday. Mixology takes centerstage at this sleek spot, where bartenders whip together elaborate drinks—dreamed up by the cocktail consultancy known as the Tippling Bros.—while patrons look on from all points. Think chic, meticulous, and about to be slammed.