There seems to be a one day sale going on from Germany to selected US destinations over Christmas 2016 and Easter 2017. Unusually, San Juan Puerto Rico is in the mix. I think because it’s pretty economically broke at the moment, I suspect there isn’t much trade. You can catch the Iberia flight from SJU to Madrid if you want to experience their A330 product, which I am told is great.
Also routings via Miami, the BA babybus from London City Airport and routes to JFK are in the offering. The suggestion above snags 140 + 40 + 40+ 60 + 140 = 420 (as American treats their Caribbean flights as Business Class).
So if you can decide today and fancy some sun, look at fares from Germany.
In addition, Singapore is offering their A380 product Frankfurt to New York, JFK in Business Class for £1,555 around the same time.
Also Frankfurt to Detroit is £1,110 and Chicago £995