Probably 6 or 7 hours. Being in a rush is a much worse experience, though, at least to me. When I went to the US and back I cut it close with pretty much every single flight. I never want to run that much ever again.

Another bad flight experience was when my luggage ended up on the wrong flight. I came home to middle-of-winter Sweden from middle-of-summer Argentina wearing nothing but a button-up shirt and chinos, and had to wait outside in the snow for a train. It was the coldest I've ever been.