United Airlines
a screenshot of a travel information

All alliances $439-$507 Chicago to Amsterdam, Brussels, Paris and Frankfurt Dec-Mar

All alliances LAX/SFO to Dublin $394-$550 Sep-May

Fare War $463-469 PHL to Dublin summer 2017 fare; ORD-DUB $497-$575 Sep-Jun

AA/DL/UA/FI $423-$539 Xmas fares D.C. airports to London, Paris, Amsterdam, Germany or Jan-March 31

AA/DL/UA $494-$649 Denver to Paris, Amsterdam, UK, Germany, Christmas to March

AA/DL/FI/UA $504-$571 Seattle to Frankfurt Oct-Mar

Delta/United LAX to Puerto Rico $275, SAN $297; SFO $303 Sep-Dec

Fare War AA/UA under $50 one-way Chicago to 12 cities

Star Alliance $538 BOS/ORD/WAS to Athens, $600s ATL/EWR/LAX/IAH Sep-May 2017

Star Alliance SFO to Dublin $503-$642 Sep-June 15, 2017