The first one that I remember was when I was 6 (very early 1970s). I flew as an unaccompanied minor from home (Buffalo) to visit my grandparents in Florida. It was either Eastern or United. I flew every year to visit them after that until I was 15, and it was always one of those two airlines. I visited the cockpit and was given a little set of wings. A stewardess would check on me occasionally and escorted me out to my grandparents after everyone else deplaned. We were served a lunch that included a roll and a couple of pats of butter. I didn't like butter, but I knew that my grandfather did, so I saved those butter pats in my little purse. Yes, it was a melted mess by the time we reached my grandparents' apartment. Airplane travel definitely meant dressing up then.
Another time I flew with my father. They had him open his brief case for inspection, and my naked Barbie doll was on the very top. My father just about died from embarrassment at that one.