will prefer an odd-numbered window seat (a or l). these seats are closer to the window and offer much more privacy than the even row window seats, as you can see below (the odd numbered seats are in the front and back, while the even numbered row is in the middle).
if those are taken, the other odd numbered window seats should be your next plan of attack, though be aware that 7a and 7l on both the 772 and 77w lack a window, as you can see in the below picture.
the same holds true for 12a and 12l on the 772 and 16a and 16l on the 77w.
couples traveling together 