Marcie anything shorter than 10 hours I find harder than the long flights. When they are long I "settle in". When they are short I am impatient to get there.
I need at least 9 - 10 hours. 4 hours to eat and watch a couple of movies and 4 hours to sleep, best to have 2 hour awake after ambien before landing (another movie) - that equals 9 - 10 hours.
The 5 - 6 hours are the hardest. Not enough time to eat, movie watch and sleep. So I forgo the sleep and it is not as good.
Did coach in the second to back row in the middle on South African airways on the long 19 hour flight. I survived. They had such a good movie selection. This is the only time I get to watch movies so I really dont mind the flying.
I prefer a long flight to a connection. The airports, security and waiting time is what tires me out. Put me on a plane and get me there - much easier. That is why I would rather go Delta or South African airways if possible.