These are all really great ideas! I also have a hard time making teens because I find them boring. I want them to be able to sneak out (like the sims 2), cause mischief by throwing eggs, ding don g ditch, toilet papering houses (sims 3). I want them to experience all their firsts including their first heartbreak (because let's face it life isn't always sunshine and rainbows). They should have house parties and slumber parties, school dances, crushes, and be able to gossip with our teens about who likes who. Have hobbies or sports to entertain them like skateboarding, rollerblading, soccer, baseball, working on cars, knitting, pottery, ballet, and so on. (Adults and kids should be able to participate in hobbies too)
As for Elders, it would nice if they could watch grandkids, teach grandkids different hobbies that they learned, show off pictures of family, set up inheritance, an option where an adult child asks them to move in to take care of them, walking cane, be able to tell stories about "back in their day".
I also agree that kids need more kid to kid interactions and kid and parent interactions. They need tag, cops and robbers, mary mac, jumping on beds, playing catch with a parent, being swung around by parent, dancing on toes, and showing off.