From sfo-ams: I like 11D or 11H. They're .both aisle seats from the center section (4 seats). This row (and row 12) is held for elite members, and are seldom filled. I have almost always been able to lie down and sleep and the seat next to me is always empty. Just make sure you spread your stuff out , as if someone else is sitting in the seats. If the plane is full, then no one else will try and join you, cold as that sounds. Do Not get Row 10, D-H, center: it is the first coach row, and when people walk around the plane, that is where they cross to get to the other aisle. Also, seat width is smaller, because the food trays come from the seat, as I recall. Also, row 36 seemed a good chance for vacant seats. But past that, the arms rest don't go up, so no stretching out. (I'm relying on memory.) Maybe don't reserve seats next to each other. So if you get row 11, reserve the end seats....it's four across. Also, call NWA/KLM and ask if the other seats are taken. From a previous thread, a seat map:
http://www.klm.com/generic/download/...aftSeating.pdf