Not a fan of JFK Flounge, primarily because it's so dark. GC is more pleasant to me, but often very busy. I normally just have dinner in the lounge restaurant and then spend about 30 mins max in GF (or GC if it is not too busy).

Am also trying my first TATL on AA later this year, though not because of the lounge, just heard good things about the 77W J product. I guess I will have to allow more time for security in T8 than T7, from the sound of it.