I get bored playing the same household constantly - bored of those sims, their house, the neighborhood and the world. That’s why I haven’t gotten very far in a legacy, either. Plus, they accumulate so much money and it’s too easy to run out of things to spend it on. By the second generation, house goals have been met and it feels stale.
Have you tried playing multiple households on a rotational basis? That’s what keeps me interested in a save. They’ll often befriend each other and hang out together, their kids grow up and date one another, etc. Then some kids might stay in the family home but others will start their lives elsewhere. For me, playing 8-12 households offers enough variety while still being manageable. By the time I play each of them for a week or so, I’m ready to start over at the top and it keeps things feeling fresh. It also makes their social lives feel more alive and real.