I want fairies so bad. I didn't have them in Sims 3, so it would be a first for me.
Would also love to see historical clothing added, just for fun. I don't necessarily need historical gameplay personally, but I'd really enjoy clothing and/or furniture. Medieval, Regency, Victorian, Roaring 20's, etc. Even stuff that's more "retro" than historical, like '40s-'70s styles. An amusement park would be fun as well, but I have my suspicions that if they did that the rides would all just be rabbit holes. But an amusement park where you can actually see your sims ride on at least roller coasters would be fun. Rabbit holes would be fine for some rides, like maybe a "tunnel of love" style ride.