Star Alliance and SkyTeam are attacking American Airlines and Oneworld Alliance partner Iberia from Philadelphia with low fares to Spain for travel departures early December to May 10. Air Canada is as low as $477 round trip, although Lufthansa seems to have better schedules at $542 round trip.
Delta and SkyTeam Alliance airlines also have low fares down to $492.
American Airlines has $495 round trip flights from New York JFK to Barcelona.
Air Canada Philadelphia – Montreal YUL – Barcelona BCN– Montreal YUL – Philadelphia
Lufthansa Airlines Philadelphia PHL – Frankfurt FRA – Madrid MAD – FRA – PHL
Delta Airlines Philadelphia PHL – New York JFK – Barcelona BCN – JFK – PHL
American Airlines New York JFK – Barcelona BCN – JFK