Winter fares to Europe are appearing in many cities across the airlines for January to March travel. Chicago has several deals with KLM to Amsterdam at $471 being one of these discount winter fares available from January 11 through March 30. The return date can be any date all the way to the end of schedule July 18 if you want to plan complex itineraries or an extended stay. You can book KLM nonstop flights or for about $4 to $10 more round trip you can fly Delta-operated flights with one-stop routings.
United also have similar fares in $470s to Amsterdam. American is $486 round trip and Icelandair $484.
KLM Chicago ORD – Amsterdam AMS nonstop
United Airlines Chicago ORD – Amsterdam AMS nonstop
American Airlines Chicago ORD – Philadelphia PHL – Amsterdam AMS – PHL – ORD
American has the most restrictive fare and it looks like low fares have a maximum 6-night stay before ticket price goes up to $700s.
Amsterdam houses (Feb 2016).