I cant answer your question about F seats, but I thought I would give some advice on flying with a baby to Hawaii. We first flew with my son at 10 months to Hawaii. Because there was a complete empty row (in the back of the plane) they gave it to us. So I sat on one end and my husband on the other. Our son only sat in the carseat during take-off and landing. Otherwise I tried to have him with that CARES harness on or he crawled up and down our seat row (on seat, not floor). No one was around and those that saw him commented that he was better than most adults passengers. I think most airlines will give you a seat selection like this if you have a baby and if they arent full. So I would opt for economy if it gave you better odds to get a few seats together/empty. BTW, not sure if you know, when they are under 2 they dont need a ticket and that also includes the stroller and carseat. No need to pay for a seat because IF they have one empty they automatically give it to baby (for free). Then just gate check (not check in) the stroller and it will so help with the baby. But if the plane is full then baby will have to sit on a lap. Its a chance you could take. We obviously did that but I picked an odd flight that I thought might have less people and I checked the seat selector to see how full. Just thought I would give you food for thought. We fly to Alaska in a few days with a now 2 year old, so i am sure things will be different (although I will ALWAYS gate check the stroller and carseat) as I have seen how the checked ones get abused.