Let me just say this: the cure to jet lag is to acknowledge to yourself that you're going to feel the same as if you had a bad, hardly-any-sleep night when you get to your destination, and go with it. Maybe that is my personal moment of zen for the new year.
I also recommend slightly longer-than-you-wish-they-would-be layovers, because it means you're not stressed out, just sleepy. It means you can buy a trashy magazine, the lipgloss you read about in your trashy magazine, a warm beverage, and chill at the gate before boarding the plane again. It means you can stretch instead of sit in a cramped locale. It means you can find an internet connection and send e-mails to your beloveds. It means that if you make an error and leave one terminal in the busiest airport in the world without collecting your bag and going through customs, you can have a do-over and still not be stressed out (you will feel stupid, but no lengthy layover can really cure that. Sorry.).
When I realized that (a) just because they turn out the lights on the overnight plane to London, it doesn't mean it's your bed time, and (b) I could really survive on very little sleep--my hell, I do it on a regular basis!--my attitude turned right around. What a miracle: the cure for jet lag in one's attitude. I might have to write a self-help book and make millions. I went to bed at a civilized 10 p.m., U.K. time, and woke up feeling almost completely myself this morning.
Lastly, reading a better-than-passable British police procedural during the whole journey made a difference. I started it on the plane to L.A., read it in the plaza at Hermosa Beach as well as on the actual beach, read it in the airport and on the plane, read it in London and finished it before I got on the plane to Aberdeen. It was called Dead Souls by Ian Rankin. It's part of a series that comes highly recommended, and there are at least eight more books in the series. Bonus!
p.s. The grandchildren, big sister and little sister, are adorable and the parents are doing pretty well, all things considered. I'll figure out how to post pictures tomorrow.