I usually start off with two sims, make them have a family, then those children get married and have babies and I usually end up with 7 or 8.
An advantage to having that many sims is that you get to explore a lot of gameplay. I have only had S4 for about 10 days now and it's hard making one sim go through everything the game has to offer, so with multiple sims I can go across multiple avenues and see what all the game offers and get more things done. There is never a boring moment when you have a large household.
Ofcourse it takes a lot to keep their needs up and sometimes I just have to queue them to take care of themselves while pausing every 2 minutes. It's a lot to take care of but if you start with just a few and go at your own pace that will get you acclimated to taking care of that many sims anyone should be fine.