University is super passive. Nearly all the game play is when you go to school and there is almost no crossover into the rest of the game beyond the boost a degree gives to job progression. I personally find college game play overly repetitive and too long to complete so I only do it occasionally for story reasons and ignore it with the majority of my sims.
HSY will bombard you with calendar notices, but you aren't actually obligated to follow the kids to school and can let them go alone. I only follow select sims to high school for specific gameplay reasons and even then its not every day. It is definitely not as easy to ignore as university though.
As far as I know MWS game play has never been fixed. I never really played weddings in the first place, and the cas/build isn't that interesting to me so I'm passing on that pack.
I have always ignored the Dream Home Decorator career entirely. I personally really like the build style and how it looks in game, so I have gotten an absurd amount of use out of the items from this pack. Easy choice here: you either like the furniture or you don't.
Parenthood gives kids a lot more purpose in the game and there is quite a bit of gameplay to go with it. Honestly to me if someone plays with kids this pack is a required add on and is more important than Growing Together. That said, off the top of my head I can't think of anything that affects adult sims outside of their interactions with children.