Air Berlin has all kinds of fare deals right now for Europe from New York JFK. One of the lowest fares is New York JFK to Warsaw, Poland on AirBerlin for $325 round trip. There are also flights from $343 to $383 round trip to Zurich, Geneva, Stockholm and Munich. The links below go to AirBerlin.com flexible search for each destination with a list of low fare dates.
Departures are available on most dates January to early April and into May for Switzerland.
Google Flights is not pulling up these fares. I see wide open availability when searching AirBerlin.com.
New York JFK – Warsaw WAW AirBerlin.com
AirBerlin.com New York JFK – Munich MUC $383.00 round trip
AirBerlin.com New York JFK – Geneva GVA $365 (April-May 2017)