The absolute best seat in Y on the 77L is 30C/G...

Sorry those pictures are not great, and in the first picture I had to move my legs over near the wall, because I was blocking the aisles



You can see here that from my seat I was sitting straight towards the J aisle.



However, you are flying with your family and while 30 C/G is great since it is the very first row in Y, but the other seats in that row can be a little uncomfortable if you have someone that is tall [at least 5' 8"] in your family then the wall can be bothersome...