What life span do you play?

I usually have the "Long" lifespan on all the time. But I am continuously changing my active household and I keep going to different households to play them. I just have so many ideas and I want every one of the Sims to live out their lives how I want them to. I know they are designed to be at least a little unpredictable and I love that, too, but sometimes I just want them to do what I've instructed..