We really need stuff for the under toddler stages. Infants are almost unplayable they're so boring without growing together and newborns have almost nothing (thankfully we can update their outfits now). As a family player I would absolutely loose my mind for more baby items (bouncers/baby swings/strollers). More occult nursery items too, it's really hard to do occult nurseries.
Elders have gotten a bit more the last few years but I would love to see more. I play my houses from birth to death so by the elder stage I am pretty invested in the characters, having more to do would be great.
We need bingo! How fun would it be to have you Sims go out to/host bingo night? That's an all ages fun game.