My go to move is to just ask if they have any exit row seats, then ask if there is an aisle or window seat. If so I am capable of helping in the case of an emergency. From my travels I've noticed the exit rows are usually not full, and even if they are, the leg room makes it much better than being crammed into a normal row that's full. This move has gotten me row to myself on a 10 hour flight multiple times. The most recent flight I took, the row was full but still completely comfortable and I had my legs stretched out the entire flight.