I have two main saves that I always come back to. One is a rotational play with all the pre-mades. My plan is eventually to have them ALL linked in the family tree as one big family. I like to put different household sims into uni together where they will develop their relationships and then they get together and have their kids after uni.
My favourite save is my Legacy save. I play each family member on a rotational basis. I am currently playing with grandchild 7/10 of the original founder. I play each family until each child has gone through uni and has got married and had their first child. It is getting longer and longer to play each family with each new pack that is released. Growing Together is going to make a massive difference to my game and I can see it taking even longer to play each rotation but I'm not complaining! There is a link to my legacy tree in my signiture.