Amsterdam ↔ Thessaloniki: €108 Nonstop Roundtrips in Both Directions w/ Transavia (Checked Bags Add €62)
Amsterdam to Athens: €118 Nonstop Roundtrips In Both Directions w/ Transavia (Checked Bags Add €62)
Europe: Icelandair Saga Class from the US East Coast Starting at $947 (Almost 100 Connections under $1,500)
Miles&More Bargains: Long-Haul Economy without Fees for 30,000 Miles + €65 r/t, with Luggage (also Possible from US)