One thing I've done for a few saves is when my "heir" ages up to young adult, they aren't the heir to the house, but rather the heir to my playing. I move them out with just enough money to purchase a new lot (sometimes that's a starter house, sometimes it's an empty lot) and then "start over" with the new generation that has to build itself up again. So I'm still playing the same family, just a different household.
I've tried to play rotationally, but I actually get caught up in whatever my current active household is doing/their story so I end up forgetting about whatever I set up in other households.