Why did President Obama deliver his farewell address in Chicago? Maybe because he has no plans to leave Washington. He’ll stick around at least until his younger daughter, 15-year-old Sasha, finishes high school in 2½ years. He’s leasing an 8,200-square-foot, eight-bedroom gray stone mansion in the posh Kalorama neighborhood, about 2 miles from the White House.

Most former presidents return to where they came from and fade into the background, re-emerging in the capital mostly for ceremonial occasions. If they’ve served two...