My favourite type of gameplay for the past few years has been to play one sim on long and keep them young forever (with whatever means) so there is no rush but things still happen and people age around him.
I do add sims to the household that I like, if I find them interesting at the time or they have a connection to my sim, I might move them out or let them die naturally (or unnaturally) or I'll give them a potion of youth if I want to keep them around a little longer.
My sim as of now is working on his villany degree and lives with the original santa (who never ages), his death by old age ghost/ vampire/ infected wife who has a huge garden but spends most of her time in the coffin because all she does is wreck the plumbing in all three bathrooms, all day long...
He has 5 vampire sons with 3 different women, one of which is an ex wife (all 3 dead by now). His current vampire ghost wife turned them so I guess in a way they do have kids together. But the 5 sons live together in a separate house.
He also have a child alien that I dumped on the other sons at first but then got back and had my sim raise him. He didn't for the other 5 so.
Lastly, the Beeda daughter, who's an elder and has lived with them for a while now (youth potions).
I had a plantsim live with them (among others like a mermaid) for a while but got annoyed how she had to turn back to human before getting the 5 day moodlet again, and that it wouldn't reset whenever she ate a forhidden fruit, so I gave her back to her parents XD.
I hope that one day there will be a possiblity to have genetic kids with an elder woman, whether that be engineering a child (like TS3 Into the Future) or another way, so my sim and his elder wife can have a genetic child.
