As an elite member with minimal carryon luggage who didn't get the upgrade, I think the 16BC are the best seats on a 757-200, as mentioned by SeatGuru. Seats 33BCDE are good, too, except for taking a bit of time to get off the plane.
If you are not an elite member, then any aisle seats that is not marked as Coach Choice would be my selection. Although on a flight that I might want to sleep, I'd select the window seat on the right side for me to lean over and sleep. Another criteria I had used was to know which direction you will be flying and stay away from the sunny side since the glare from the sun makes it difficult to see my laptop monitor.
I hope this sort of helps to make your choice.

HJ