UPDATE: United Airlines is in the game also. See https://cheapdfw.com/cheap-flight-dallas-eastern-europe-ireland-nordic-ua-dl/
ORIGINAL POST: Destinations include Athens, Barcelona, Budapest, Dublin, Lisbon, Madrid, Prague, Shannon and maybe others.
Departing from Boston, Chicago, DFW, Los Angeles, Miami, New York, Philly, Phoenix, Portland, San Francisco, Seattle, Washington and probably others.
Most round-trip fares are in the $500s and $600s.
Travel dates extend now until early May, and late August to October.