What are some underrated features of your favorite packs?

The entire parenting system from the Parenthood. Your adult sims gain specific traits and interactions based on how they were raised. For example I had a female sim who earned the good manners trait. She could do a polite introduction to new sims she met during which she could walk up and shake their hand. I loved it, it was especially handy once I put her in the political career. It looked so authentic to see her going up and shaking hands before lobbying people for their vote.