There's no nonstop path between O'Hare and Bilbao's compact Loiu airport, which means every itinerary in business class from Chicago to Bilbao routes through a European gateway—and after dozens of trips on this corridor, I've come to see that connection choice as the single biggest factor in how the journey actually feels. Iberia via Madrid is the natural choice given its ownership of the Bilbao route, and their A330 or A350 business class cabins on the transatlantic leg, followed by a short intra-European hop, keep the itinerary tidy and largely within one alliance. British Airways routes through London Heathrow, where Club Suite—with its sliding door and direct aisle access—makes the long transatlantic segment genuinely restful, though you'll want at least a 90-minute connection buffer at T5 given the security recheck. Lufthansa's option through Frankfurt or Munich brings their newer Allegris business seating into play on select aircraft, though it's worth confirming the specific configuration before booking, since Lufthansa's fleet rollout has been uneven.
Madrid-Barajas remains my preferred connection point for this itinerary: Iberia's business lounge there is spacious and rarely overrun, and same-airline connections mean checked luggage typically sails through without incident, a real advantage after a nine-plus-hour crossing. One insider habit I've developed is booking the Iberia routing whenever possible during the Basque Country's shoulder seasons—autumn rain and winter fog occasionally disrupt the short Madrid-Bilbao hop, and same-carrier rebooking protections make Iberia far less stressful than a mixed-alliance itinerary if weather intervenes.
January through March and again in October and November consistently offer the softest fares on this route, as Basque tourism dips outside summer festival season and before the winter holiday surge. Given how much itinerary pricing on this corridor fluctuates week to week across three carriers and multiple hub options, setting up fare alerts is genuinely the smartest way to catch a strong business class value before it disappears.
