I haven't flown premium, but did consider upgrading on my last flight. I will usually wear a sportcoat and trousers (I find trousers more comfortable than jeans, they just drape better) depending on destination (brought it along to Chicago where I saw the Symphony Orchestra, and brought it to Austin, where I had a tasting menu). The sport coat allows me to carry extra items/sit more comfortably with them in my pockets. An extra layer I can remove/add depending on temperature in the cabin. I did notice at check in, some of the airline workers who were guiding people to the security lanes assumed I was flying first class/status.