Star Alliance partner airline TAP Portugal has one way fares at $314 from Boston, Miami and New York JFK to Amsterdam, London, Paris, Frankfurt, Munich, Prague, Zurich, Vienna, Milan, Rome, Barcelona, Madrid, Warsaw, Helsinki, Copenhagen, Stockholm, Oslo and several other cities in several of these countries for departures from September to April 2017.
Fares from BOS/MIA/JFK are $299 one way to Lisbon and even down to $251.20 for New York JFK to Porto, Portugal one way.
Google Flights Fare Map Boston – Europe One Way filtered for Star Alliance
Low fares to Portugal, Spain, France, Italy, Switzerland, Austria, Germany, Czech Republic, Poland, Finland, Sweden, Norway, Denmark, Netherlands, Belgium, Luxembourg and England are places where I see $314 one way fares on TAP Portugal.
TAP Portugal New York JFK – Lisbon LIS – Porto OPO
$251.20 one way Monday Sep 12 ($239 on Momondo.com, but longer Lisbon layover)
TAP Portugal Boston – Lisbon LIS – Rome FCO
Note: Flights connecting to other European cities tend to have 12 hour all-day layovers in Lisbon. I view this as a bonus feature of the ticket price. You may feel differently about an all-day layover after an all-night flight. A sign on a wall of a Manhattan building in SoHo I read in 2012 kind of summed up my thoughts on fighting jet-lag: “You can sleep when you’re dead.”
TAP Portugal Miami – Lisbon LIS – Prague PRG
One-way fares intra-Europe are very low to get to a city with discount one way fares on Norwegian, WOW, JetAirFly, Eurowings and other low cost airlines back to Boston, New York and Miami.