I've flown FF a few times, JFK-LAX, SFO-LAX, MIA-LAX.
For MIA-LAX they gave me a brief runaround about FF checkin, I'm not sure why. Although it really wasn't that big a deal. What WAS a big deal was that my flight was at 1:35 and FF dining didn't open until 1:00. I actually sat behind someone who said he had scarfed down a lunch after they opened and was the last one on the plane. He was younger and more mobile than me, so I'm glad I didn't try.
I don't really fly for the food, so I can't comment about the onboard food. But there was only a microscopic difference between the J and F seats on the 77W, and really none on the A321T.
The FL was closed in LAX, and I'm not sure whether there even was one in SFO. However I did get FFD on JFK on both the outbound and the return. Like many things I am reminded of the Dom DeLuise line as Caesar from "Mel Brooks History Of The World Part I" when he is presented with a bathtub as a gift from one monarch to another - "Nice. Not thrilling, but nice."
These were all deeply discounted trips, the MIA-LAX was about $1000 and the two from/to JFK around $1200ish. I wouldn't even think of booking them at current prices. I might spend an SWU on one, except that the Flagship Biz tickets I have booked are for red-eyes LAX-MIA,and I'm not sure it's worth it basically just for FFD at LAX - which whenI was there last, wasn't even open.