If you like playing families and having parties, I recommend Generations. That is the most realistic addition to the game, in my opinion. I enjoy having pillow fights, giving flowers, bachelor/bachelorette parties, more realistic weddings, tree-houses, graduation, water slides, the list goes on and on.
Late Night is all right, I like the Film career and Bridgeport is fun to play in, but having celebrities and vampires everywhere gets on my nerves sometimes. I wish I could turn those features off. How much sense does it make to have celebrities and vampires living in Riverview?!
I just got Showtime, so I haven't played with it too much, but I do enjoy the genie feature very much. Their magic powers to clean the house and Sims instantly, ensorcel Sims, and summon food come in very handy. It's like cheating without cheating! I am looking forward to having singer Sims and that, having the Diva and Natural Born Performer traits will be fun for making a selfSim, but like I said I haven't played too much with that yet.