AA 1373 JFK 07:45AM MIA 10:40AM 762
AA 944 MIA 12:40PM MCO 01:38PM 738

The JFK-MIA flight is a two-class flight that operates on a three-class plane, so as an AA elite, you could pre-reserve one of the J seats, albeit with Y service.

I do a lot of crazy things for miles, aircraft type and seat comfort, but I don't think I'd turn a two-and-a-half-hour LGA-MCO flight into a six-hour trip for a J seat.

The return flight is a little more efficient:

AA 1373 JFK 07:45AM MIA 10:40AM 762
AA 1325 MIA 12:40PM MCO 1:38PM 738