I tend to make a family, turn aging off and just watch what they do. I will make babies and age up sims, then those sims will have babies. But, I like to stick with a few sims and follow them forever.
I've recently started a legacy save. My first baby is already a young adult. It feels weird after playing with aging off for so long, it feels like they are aging way too fast. The sim in my profile pic would be a great-grandfather by now. But, it's giving me time to max a bunch of skills and work through all the aspirations.