United's Europe offer includes cities in both Eastern and Western Europe, such as Frankfurt, Rome, Prague, and Warsaw. Book tickets by Monday, May 26.
American's new sale competes with AirTran's latest offer, so you should compare fares from both airlines before you book. Cities include Boston, Chicago, Los Angeles, and New Orleans.
American's offer features flights to Milan, Paris, and Zurich. Departures are valid in June and July.
