Enjoy the food, wine, service, excellent hard product. I'm not sure what more one can get out of a flight.
In terms of lounges the difference between J and F is huge - much less crowded, free spa treatments/ shoe shine, better service and a la carte dining.
What you can safely miss out - trying to have a shower unless it is on the 380. Lounge showers are some of the worst I've seen at F lounges.