Normally, your flight should be AirBus 330 type. I recommend row 22 to 25 which is the front part of the economy class and easier to leave with the kids. Try to ask for the Seat A & C. Seat A is window seat and Seat C is aisle seat. Since your flight is in the morning, therefore Seat A (left-hand side of the plane) can avoid direct sunlight from the east when flying in the northward direction. You've got 4 persons and so get 2 consecutive rows of seat A & C, e.g. 24A, 24C, 25A and 25C.
Avoid Row 27 to 36 the sight through the windows will probably be blocked by the wings. So if you can't get the front seat, get the Seat A and C after row 36 to secure an unblocked view. Or otherwise, you may choose Seat H & K on the right-hand side, although the sunlight may be quite fierce and you need to have the blind pulled down sometimes.
I can only base the my experience and the normal seat plan to advise. The seat plan may vary sometimes depending on the actual flight model used. Hope my little suggestion can help.
Really sorry. I need to correct some information. The wings of the plane should block part of the view of row 22 to 30 and not what I have said before. So for economy class, choose seats after row 30 should have better view.