It'd be cool to be able to play the kid Sims at school, and for things like scouts, ballet, etc.
It'd be cool to get a new pack that gives preschool for toddlers, and boarding schools for children, pubescents, & teens. And, for it to give us a pubescent life stage. It could include a lot of major things missing.
It'd also be great to get daycare back. They removed daycare from the game, and converted people to having to remember to call a babysitter an hour or two before work. And, they never remember to call the babysitter, just leaving all ages of minors home alone when at work. I'm finding the only good option is to have a stay-home parent, because whenever both parents work, they ditch the kids home alone.