One of my favorite saves has TS1 and TS2 characters in it. The ages really vary from prior games though. I really enjoy playing out their stories though in Sims 4. I play in rotation and very, very slowly since I play other saves also.
I have the Specter Family from Sims 2 but Olive and her sister are teenagers still and living with their parents. I'm waiting for a job or some other spooky pack to make it right for me even though I've got her backstory going of how she gets involved and influenced by the grim reaper as the family cemetery count rises. I just don't want her to grow up and start dealing with her husbands deaths yet. Even Buzz Grunt's wife is still alive in my game although she's infected/possessed. It will possibly add to her story as to why she ends up in the Specter's graveyard.
I really enjoy playing Don Lothario as he was presented in Sims 2 .. he's a real ladies man of course.
I have the Beaker Family (sadists) and Curious Family also but they are a little before Sims 2 time line also.
The Grunt Family, The maids from Sims 2, Actually Remington is a pretty central character but Kaylynn was made to replace Don's maid and add to the drama. I also have the Pleasants as they were in Sims 2 and The Broke Family with Skip still alive and well... actually he's a young adult and Brandi is still growing up and living with Bob and Betty Newbie. Darren Dreamer hasn't even met his wife yet either although I have his future house waiting for him to move into.
From the Sims 1 families like The Hi.cks, The Charmings, The old Goths, Ginia Kat.... and more overall from both games.
It's a fun way to play.