No. I don't believe in dressing in gym attire or beach attire unless I'm going to the gym or to the beach. That said, when I am traveling, I wear comfortable clothes that clean easily (I am notorious for spilling salad dressing and Diet Coke all over myself during turbulence, and I have learned to avoid soup and anything involving tomato sauce in flight). My "uniform" is knit trousers (you'd have to look closely and carefully to know they are knit) in a light or mid-weight wool, turtleneck, and sweater three seasons of the year. There is usually a silk scarf tied around the handle of my handbag, so that I can wrap it round my neck if the cabin gets cold. I wear my heaviest shoes, then remove them on board and wear slippers. In summer, it's a much lighter variation of the same. If pjs are offered, I change into them.