I wear a tunic and pants set from Citiknits. They sell them on QVC. Not necessarily the most stylish outfit - they're polyester knit with an elastic waist - but very comfortable. I have it in black and dress it up with a colorful scarf and a nice bag, of course.
I fly trans-Atlantic a lot and need something I can comfortably sleep in, won't wrinkle and can be washed out in a hotel sink for the flight home and this fits my needs.
I've worn jeans but I wear my most comfortable pair of jeans since I'll be sitting for at least 5 to 6 hours on a plane. A t-shirt and a light jacket and comfortable shoes that I can slip in and out of easily.
Comfort first, especially on long-haul flights. I like a knee-length swingy skirt so I can sit cross-legged. I wear mostly crocs onboard now because the feet expands. One time I couldn't put on my shoes after having them off for 13 hours!
I wear linen pants, shirt, and Dr Scholl original sandals. Plus when I fly across continents I keep a pair of Juicy velour hooded tracksuit and a pashmina in my bag, and I change into these in the toilet so I can fall asleep.
For short flight I wear everyday clothes.
Comfort comes first for me when I'm traveling long distances!
We are driving to Paris in about a week and a half and I just plan on wearing tracksuit bottoms and tennis shoes or flip flops (depending on weather)...I hate sitting in the car in jeans for some reason :s
if i fly to somewhere warm i wear leggings and a short dress with ballet flats, and i bring flip flops in my hand luggage in case my feet swell or it's really hot. if i'm going somewhere cold i wear a fairly similar outfit but with flat boots and a coat. long haul i usually change on the plane, i wear something like yoga pants, a t-shirt and a cashmere sweater for sleeping. never jeans or anything tight on the plane, i get all fidgety if i'm not comfortable.
dress thights loafers, i always have an extra shawl for longhauled flight from uk to singapore and vice versa. i'll usually do the transit at dubai that's when i stripped off the thights b4 flying towards singapore!