I prefer to do personal dynasties. Start out with the married couple, they have two or three kids, then one marries and the other(s) moves out. That couple has two or three kids, same aspect. I tried to keep all the family members there, but I don't have the mods and it became too frustrating to keep track of them all, who needed to do what and when. Turn around and the one you sent to eat and then to bed was in the study reading and in the red from hunger and energy because someone stopped to chat and they didn't do as told!
The stupid relationship glitch is really messing that up a lot. I haven't been able to get any eternal faithful moodlets, and I am spending a whole lot more time that needs to be to delete letters and the hassle of gifts for seven family members present and one on the way along with keeping track of what the are all doing. It is taking all of the fun out of having a good size family, especially when I have an extended lifespan, not the default.
Right now I have three families that are on their third generation and number four is on the way. I am going to have to move out the oldest couple when the next generation is born, keeping just the grandparents there to help out until the children reach teen years.
I used to just randomly pick out careers, whatever fit with what I was interested in. But I have decided to create a set goal borrowing from the challenges here. Go to 10 generations, no one having the same career as the others and other aspects that will make it more interesting for me.