On my last flight from CPH to LAS and back again(about 10 hours each way). I booked a 1000$ seat instead of a 500$ seat to get a "premium" seat, and it was worth it. I could open my laptop and play games, I there was room for my legs and even to each side in the seat, I could even recline my seat enough to get a decent nap.
But often you don't have the option of a seat double the price, you have to pay three or four times as much as the next step up.
I have been traveling with other people that are below the average size for scandinavians, and that always say that they have no problems with the small seats, and yet their elbows are always entering my space. :)