I really like the idea that after the kids have grown and left that when one of the parents dies, instead of that parent having to live alone and be lonely, you can pick a grown child to move back in but the parent just moves into the kids' old bedroom and continues to live in the house until they die. I hadn't had anyone die until just a few minutes ago and, unfortunately, not only was the remaining spouse really depressed, but her dislike was "solitude" so no matter what I tried, I couldn't get her happy again.

I finally decided to pick her firstborn to move back in, not knowing that the mom would be gone forever once I did, only to discover that now the mom no longer lives there. I thought the daughter could move in and live there with her mother. Oh well, at least the daughter started with lots more money than her parents had and a nicer house as well.

eta -- Lizzy, I like a lot of your ideas. I just wanted to say that I had a family whose only son had grown and left and then a little boy came to the door needing a home and I had them adopt him. He was 6 at the time. Then, a short while later a little girl came to the door needing a home too and I had them adopt her also. She was three. So the ages definitely do vary at least.