For a little spice, you could make your sim have the ultimate goal of fixing up the rundown home and achieving immortality. By definition, immortality is the inability to die. So, it's more than just making your sim live forever. It would include unlocking all the traits that make it very difficult to kill the sim. Things like never starving, immunity to death by lightning, cold, and heat. Immunity from death by embarrassment and the ability to remove negative emotions faster. The naturalist (Freelance Botanist Aspiration) trait would make your sim immune to fire.
As for some other things that might help with different stages, traits gained from different aspirations are a good start. For instance, a handy sim can instantly upgrade appliances, and the different stages of different aspirations can mark different stages.
