My choice for the CPT-AMS is ALWAYS row 6 if available, I usually watch a movie at takeoff and have something light to eat, then by the time the movie ends so does the economy service and it's fairly quiet, if you are sensitive to noise then it might not be the best seat for you but for me once I put the earplugs in all I hear is the white noise from the engine.
Given the 11+ hours of night flight, I usually get 6-7hrs of decent sleep, then wake up and watch another movie or do something else shortly before breakfast service starts.
For the AMS-CPT, whichever is closer to the door, usually I like row 5.