I have only flown Y in the 3-4-3 configuration on shorter flights, LAX-DEN and DEN-IAH (both "island" configuration 777-200s with the old business class cabins reused as first class seating). It's the shoulder space that really suffers. Once I had a middle empty next to me, the second time the adjacent passenger was very petite. I would dread facing something like SFO-HKG (on the 777-300, also 3-4-3) in this configuration.

my family are all pretty slim an the toddler will be sitting between my wife and me so it's not so much the width that is concerning. it's more the the firmness of the seat bottom cushion. i need firm cushions because of my back. i have suffered several times due to the domestic seats on carriers such as old south west or american having seats that sunk in at the bottom as soon as you sit in them.

I recently did a return trip, outbound in the new 3-4-3 and return in the old 3-3-3. Both seats seemed equally hard, at least as compared with the old 2-5-2. As I had the middle seat empty between Mrs LHRSFO and me on the new sardine can, it was better but only for that reason.

If your problem is only with the seat bottom cushion, that is very easy to solve. There are many products in the market for that problem. At one point I was worrying that you needed support for the whole seat including the back area. A seat cushion should be a good investment for you if you plan to travel often as then you don't have to worry about which plane type you get. On my 6 flights this year that were supposed to be on the pmUA 772 (3-3-3), I got 3 flights on that configuration, 2 flights on the Polarized 772 (3-4-3) and 1 flight on the pmCO 772. So, you never know what plane you get until you are sitting in it.

Thanks. that helps!

It also depends on the shoulder width of your seat-neighbor. I think most people have wider shoulders than hips/butt, so squeezing into a narrower seat is more easily accomplished than leaning out to accommodate a wide-shouldered person in the middle seat (of which there are 33% more on the 3-4-3).

Instead of being at the mercy of the seat, try


When not inflated, they take up very little space

I have the Thermarest (2nd link) and it literally saves my arse on 12+ hour transpacs, and even transcons and mid cons. I have used it about 30-40 times on longish or ULH flights.