Thanks for the insights. My ideal situation would be to use on a newer plane like 330 or 777 without Premium Economy so I could upgrade directly to Business and on a westbound day flight. IST-SFO seems the best for that. I have found my best sleep in Y was in relation to the later the departure, the more chance of sleeping. Having taken a 6p departure before, sleep seemed impossible! At the same time, I am old school in thinking that middle seats do not belong in premium cabins.

Additionally, my experience has been lacking on Europe - Asia flights. Felt more like crew just going through the motions as opposed to Transatlantic and Transpacific flights.

As it costs same amount of miles to upgrade as it does to book an award for one segment, I might just save the miles for the return.