When I do this, I usually just do one or a few households. The gallery can help a lot to replace lots within one specific neighbourhood. I don't have the time or patience to change the rest of the world. That would make it too long before I can start playing them. So these sims will run into Bella goth, the caliente sisters and all the other townies.
I just see where the game takes them. So their lives are influenced by what the game has to offer in terms of gameplay (for example careers, hobbies aka skills,..) and (unfortunately) modern technology like phones and computers.
I also try to avoid cc.