There is no real advantage of being seated in the first economy cabin in terms of comfort versus the rear cabin so get a seat in the 30s so you won't get the wing in the way of a view. The first rows of economy are towards the middle-rear of the wing but still obstruct your view. I'm a window seat gazer and always pick row 34 - you'll find the window perfectly positioned - trust me Also much quieter here as the aircraft always fills up from the front.