The window displays at Mr. Sid would have Simon Doonan himself pulling out his pocket square to mop sweat from his brow; inside, it only gets better. Browse 15,000 square feet of clothing, shoes and accessories from Ermenegildo Zegna, Brioni, Alden and more, or head downstairs to the gentlemen’s salon for a haircut accompanied by some bourbon or Champagne. If your finds need some adjustments, the master tailor, considered a “surgeon for clothes,” is at the ready.