As for differences between F on 777-300 and 777-200 - no difference in the seat; a few of the 777-200 still have the old IFE; an a couple of them have a weird cabin layout which is missing two seats down the back right side of the cabin (replaced by crew rest area) which makes the K-side of the aisle a little quieter - 2k is a nice seat on those planes. Otherwise, all the 777 F cabins are essentially the same.

I've only ever managed F on a 777 (quite a few times, but always the same plane!) so can't compare to 787,747, A380 etc