One other thought: Premium Economy roundtrip fares from Upstate New York to London tend to be significantly cheaper than such fares where the roundtrip starts in London. If you are able to book your travel significantly in advance, perhaps you could find a way to get yourself an inexpensive one-way (maybe by redeeming frequent-flyer miles?) from LON to Upstate New York, and then purchasing your subsequent roundtrip (or open-jaw) tickets with an Upstate New York origination.