Seven airlines compete for this connecting market, each routing you through a different gateway. United's Polaris product connects via Newark or Washington itself with onward European legs, giving you a lie-flat pod in 1-2-1 configuration and access to the Polaris lounge before departure. British Airways routes through London Heathrow, and its Club Suite is worth seeking out specifically for the sliding door — genuine privacy is rare on connecting itineraries, and this cabin delivers it along with White Company bedding. Lufthansa's newer Allegris suites, flying on Airbus A350s through Frankfurt or Munich, represent the airline's most significant business class overhaul in years and are consistently among the best hard products on this route. Turkish Airlines funnels traffic through Istanbul with excellent DO&CO catering, Finnair uses its Helsinki hub (a genuinely efficient shortcut for northern European connections), SAS offers a Scandinavian-to-Scandinavian routing advantage through Copenhagen with a short hop up to Aarhus, and Air France connects via Paris with its usual strength in food and wine service. For onward connectivity into Aarhus specifically, SAS through Copenhagen is often the smoothest, since the final leg is a quick regional hop rather than a long-haul-to-regional grind.