A: I'm not one of those paragons who arrive pressed and perfect. Looking semi-nice is a more realistic goal.
Cargo pants are as relaxed as jeans but looser and have all those useful pockets. Layer your tops—like a long-sleeved tee over a tank—so you're prepared for blasting air-conditioning and the sweltering moments without it before takeoff. Unless you're planning sprints down the aisle, avoid nylon jogging suits; they're no longer hip and were never very attractive.
Then there's security. Beware of anything that will set off metal detectors, like a belt with a huge buckle (besides, who needs two seat belts—not comfy). Save time with slip-on shoes—and wear socks or hose so you're not going barefoot on the terminal floor (or in the plane itself, where the carpeting, I swear, has cooties). Flats work best for the long march to your gate.
What to skip? Perfume. When my seatmate has overdosed on fragrance, I want to gag.