As a regular on the JFK-LAX route, here is my take:
1. The F Class seat is a slighlty modified version of the CX & AA 77W international business class seat.
2. They will upgrade from J to F but because the upgrade list is based on AA EQDs and Transcons are heavy with AA EXPs the chances of non-AA elites getting an upgrade to first is probably low. I would not be surprised if the route is popular with AA EXPs looking to cash in their SWUs as well.
3. As the EQD list is dynamic the upgrade list can be pretty fluid almost up to departure. The Transcons also have a lot of flexible travellers. It is frustrating to see 4 empty seats, be number 4 on the upgrade list 20 minutes before departure and then a higher EQD person comes along............
4. AA has a lot of media corporate contracts which is why F is on the Transcons, I think Disney is one of the biggest. So if celebrities are your thing there is a good chance of meeting one in AA F. They are usually boarded separately.
5. The J seat is not too bad, lie flat, and although 2-2 I have met some very interesting people on these flights.
Good luck to the OP if he gets lucky then it is a nice experience. The AA Flagship dining in the lounge is usually good and in the small side lounge with bar the staff are excellent.