I tend to make a new save to try out each pack, but am trying to stick to one save now so that I don't forget sims I loved once. My simself and my daughter's simself are background characters in most of my games. I make an effort not to make friends with myself, just enjoy the occasional out-of-character cameo.
My current big save was made for the werewolves pack. I amused myself letting my Sims have a whole litter of children, then tried rotational play with each of them. Mom kept calling up and asking for more babies until the house was full again, so she's got eight total, two of whom are married with kids of their own. There was a story progression glitch where one of my founder's daughters was pregnant every time I got to her, so she has four, when she was meant to have one.
I am so attached to so many Sims now that I can't even decide who to play, and if I try to rotate on a strict schedule it feels like a chore, so I pop around to whoever I feel like when the game opens. I've decided to play as my simself for the first time! My simdaughter and Simself moved to San Sequoia right across the street from the water park, but I've gotten used to really large houses, and am considering adding rooms. I think I'll make friends with the werewolves, so they can invite themselves over. Funny thing is, though my legacy is 90% werewolves, Spellcasters are my favorite, so I'm going to become a Spellcaster. Nearing the end of Sims 4's run, there's finally enough funny chaos for me.