TAP Portugal has had one of the best sales to Europe for the past couple weeks and $480 round trip to London Gatwick LGW is another deal available today. Departure dates are October 2 to Dec 7 at $480 to $503 most dates.
Many of the dates I checked require an overnight in Lisbon on the return. There is the possibility to get nearly a 22 hour overnight layover in Lisbon, Portugal on the return for a good sightseeing opportunity on a ticket to London.
TAP Portugal Miami MIA – Lisbon LIS – London LGW – Lisbon (21 hr 40 min overnight layover) – Miami MIA
$483.78 round trip Sun Nov 20 – Sun Nov 27 (Thanksgiving week).
Loyalty Traveler – TAP $313-$318 one way JFK to 11 countries, 30 cities (Sep 2).
Loyalty Traveler – Fare Alert $314 one-way TAP Portugal BOS/JFK/MIA to 17 countries in Europe Sep-April 2017 (Aug 24).