We have toddlers, now, so if you're in any way a family-oriented player, you're going to want Parenthood. This allows you to help direct your little Simmies in the way they should go. There is a Values system that the parents can teach their children to have starting with the toddler. The earlier, the better. Sims can set the table which helps to make the family sit together for a meal. It also helps them to gain manners.
If you're interested in stardom, I am really loving Get Famous. I think the celebrity system beats the one in Sims 3. Not everyone is a celebrity, and although there is supposed to be a way for your would be star to get a boost from knowing a celebrity, I haven't found it. LOL My Sim has worked his fanny off to get where he is.
If you don't mind having mods in your game I recommend MC Command Center, which allows you to set things to simulate story progression, plus a number of assets.
City Living also gives your Sim an actual singing skill.