We played part 1 of an adventure that returned to the setting of a campaign I ran in the Frontiers of Alusia from 1985 to 1994.
I had one of the original players, N.A.B., and my daughter and my niece and nephews for players. It was fun to see N.A.B.'s face when he figured out where the adventure was set, and that the old characters were in the same city as the new characters, and how he insisted the new characters get as far away from the old characters as they could. (I hadn't planned on there being any interaction anyway.) And the kids and I had fun.