An aside: as I wasn't old enough to have a credit card yet, I bought the ticket by walking into the Pasadena office of American Airlines with $480 in sequenced twenty-dollar bills. I don't know what would happen if I tried that today. Do airlines even have local offices any more?
The trip back was a marathon 20-hour trip beginning in rural Vermont by bus and involving a change of planes in Chicago and a change of airlines in San Francisco before finally returning home. I had quite a bit of stuff with me: clothes for two different climates, promotional material from the colleges, random gifts from east-coast relatives, and so on. And I was used to checking bags for cross-country trips; they weren't made lightly in a family of four. So at the risk of missing the connection at SFO while waiting for luggage, I checked a great big bag at Logan airport.
Immediately upon getting on my first of three flights for the day, I realized my mistake. The airplane was nearly empty, and after a stop in Chicago, it was continuing... to LAX! Airlines weren't paranoid enough to count passengers back then, and I'd surely have been able to get away with staying on the plane. But while I'd have gotten home six hours sooner, my luggage would have been stranded in San Francisco. So I got off the plane I wanted to be on, and got on the one with my bag in it. Sure enough, it made the connection and popped out the baggage claim, the one time I'd wished it wouldn't have.
SFO is a huge semicircle of gates and gate complexes, curving just enough to keep the sightlines down but not so much that you can really make a shortcut across it. It takes about five minutes by careening Smarte Carte to travel from American Airlines at one end of it to Alaska Airlines at the other. Not a measurement I imagine the folks at the airport wish to have recalibrated.
And so (o best beloved) the reason I don't check bags is the opposite of what you'd expect: I've only ever been burned by my bags ending up in the right place.