TUPELO, Miss.—Its sheer size defies gravity. Its grace and elegance defy reason. The Boeing 747, mother of all jumbo jets, is in its twilight years for passenger service, leaving multitudes of travelers nostalgic for a time when air travel was comfy and exhilarating.

Only 180 of the original jumbo jets, dubbed the Queen of the Skies, remain in passenger service. Boeing Co. built more than 1,500 of the 747s—passenger and cargo—but is unlikely to be building any more of the passenger variety; the 24 orders that remain are all...