I would go along with all of the above for 99% of the fish you likely to encounter 200 yards will be plenty.
Just remember that if you spend enough time on the flats you will one day encounter that 1% fish of a lifetime. Maybe a 50lb Permit that, on that particular day, cosmic forces have decreed with be the day it meets YOUR
fly and says "yes".
I carry as much backing on the largest large-arbor reel that will comfortably fit on my 9wt. That way I know I will be ready for Mr. "One Percent" should our paths ever cross