I start a lot of new "side saves," in which I might try small, different things. My daughter and I have started redecorating houses, and we'll decide to put one into our game...and let a Sim we've never played before live in it. Presto, new save. Or, we'll populate a world with newly-created Sims (Z loves CAS), and see what they get up to.
This playing style helps us avoid becoming sick of our "story save," which we don't want to mess up by trying new things. Occasionally a "side save" will turn out to be so much fun that it becomes the save we choose to play first. Or, a Sim we enjoy from a "side save" will be brought into the "story save" as a recurring character/"supporting actor."