I, honestly, tend to do a bit of everything with one full household. Family gameplay, laundry, dust, seasons stuff, haunted house, restaurants, spa, gardening, different careers, usually occults, sometimes off the grid, sometimes pets, occasional vacations, occausional University run through, etc. all in one family.
It probably boils down more to how you play, but I've always been an "everything and the kitchen sink" type with playing DLC. No division necessary in my mind.
I agree with doing multiple households if you need that division; multiple Sims in a household if you do not. My most diverse saves tend to be ones I really stick with, so devoting the time to really live out a particular Sim's or Sims' lives might be really fulfilling for you since you can have them go through stages in life.
For example a YA that climbs the celebrity ladder only to throw it all away for a childhood sweetheart in Henford on Bagely. After farming by his/her side with their now young children (s)he yearns again for the urban life like (s)he did in their shared youth. They split, and through the fulfilling single years in San Myshuno (s)he is now ripening in late adulthood. (S)he discovers a love for forensic work by chance and pursues this new dream in life, working along the way into a cozy retirement with a retail store on the side. That sounds like a pretty amazing concept right there, and totally doable. You don't have to commit to any one thing.
