When I fly the longhauls I usually dress in suit and tie at checkin and pay F or C full fare. It helps me pack more sloppy for the other cloaths and then I have the FA hang up the suit coat.
However when traveling paid R class I go back to sloppy attire to make sure that I'm not considered deceased at the end of the flight.
From what I've observed the older men in this class look like they've been embalmed, they're so well manicured.
