I know that this is just a game but with Story Proggression there are so many possibilities. e.g Hair Grows (Hairdressers) Grass and Plants Grow (Lawn Mower and Gardener) Sims grow taller gradually (Not just for a birthday, they have already done it with outwards)
I'd quite like to see some expantion packs for pets, magic, seasons, Businesses, University, Nightlife (I know thats basicly all from ts2 but How many more catagories are worth putting in?) In Pets well not just Hamsters, Dogs, Cats, Birds. I think more pets like Reptiles, Rabbits, Guinea Pigs, Turtles, Fish... and also wild animals like wolves, foxes, badgers, rabbits, deer, ducks, birds...