I have clients who like yourself only went BA Club. 1 try on AA on the 777-300ER and they will only fly AA where they fly instead of BA (provided flight has this plane – small chance can be plane changed for technical reasons).
This should show a good picture of the cabin. If you can try and get Row 3 or 4 as mini cabin at the front of the plane behind 1st Class. And keep an eye on check in online for upgrades to first – 2 out of 3 return flights when seats available back from NYC they were offered for £275 / $410.
JFK should be also all 77W but had 1 technical that I have heard of and old plane subbed (which is awful). LAX also all 77W. 1 DFW and 1 MIA are new 77W (777-300ER) – but other flights that day are old product.