Delta and Air France have round-trip flights from Atlanta (ATL) to Porto, Portugal, Valencia, Spain, Poznan, or Krakow, Poland (OPO, VLC, POZ, KRK) for $514-$526 with a connection. Flights January to March. Departures on Monday, Tuesday, Wednesday, and Sunday. 7-day minimum stay required.
A Carry-on bag and also a personal item is allowed for free on Delta. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.