LGW - Air France has never flown the 777 into Boston. They use the 767 with a 747 mixed in about once a month if even.
As a BOS user though, it is HORRIBLE to fly out of. There is so much congestion that we are trying to build a new runway to reduce delays, and we want airlines to move flights to Manchester, Providence, Bradley, and Worcester to allivate delays. As for photo spots, BOS is one of the most photo friendly airports in the country.
We also get a lot of variety, with 717, 727, 737, 747, 757, 767, 777, A300, A310, A319, A320, A330, an occasional A340, and all the normal commuter planes.
Plus, you can see it from anywhere in Boston facing the airport or its runways as least as it is high up (I have seen 747s land from the 27th floor of the Westin.)
BA747-436 - Sorry to disappoint you, but BA is switching to all 747-236Bs on BOS-LHR next month.
So to summarize, it is a nightmare for flights, but it is superb for photos.