Chicago is a magical city year-round. Winter provides ample opportunities to ice skate under snow-kissed skies before dashing into hole-in-the-wall restaurants for deep-dish pizza or Chicago-style hotdogs—while summer reveals a city set abloom with irises and lilies, best viewed by river cruises or sailboat charters. The only question is where to rest in between action-packed days.

The Peninsula Chicago—which is scheduled to complete a major renovation of all 331 guest rooms and suites this April—provid…