The reason DAL has the ATL-MCO flight is so pilots remain qualified in their landings. AA does this with repositioning flights from MIa-DFw, DFW-ORD, LAX-MIA and others I can't remember.
Japanesse airlines operate 777 in Japan very ineffiecently, 777-300 seat close to 400 people. I don't know how many hours this birds spend in the air but, 6 hours a day sounds right.
777-200ER is AA international airplane, it is configured with all the extras for 7 hours to LHR and 13 to NRT, EZE & GRU out of Miami too, ETOPS ecquipment, extra galleys to serve 2 or 3 meals a trip, entertainment systems; this airplane is the 747 for the new millenium with 2 engine effieciency. IF you want 2 class 777's, Thai air has a few for sale already to go, 8 seats across in Club class with Rolls Trent engines. Hopefully the day AA uses a 777 from SJU it will be to Mad or London.