Currently, my rotational play is based on career. That is, when I log in to my game I ask myself what career I'm in the mood to play. Example, I'm in the mood to play my veterinarian, so off I go to the clinic and develop this character and career. If I'm in the mood to play my self sufficient artisan sisters, off I go to develop their characters and skills. So far, i have a lawyer, a business tycoon, a veterinarian, and will be adding more to the rotations. Along with their career choices, my characters have their own personal stories, backgrounds, ambitions, etc. As well, I have some of these households interact with each through friendships and sometimes romance, marriage and parenting to get ready for the next generation.
I was finding my usual style of gameplay was becoming a bit stale. I just started this type of rotational play recently in order to explore some of the careers I've not yet done. I'm finding that I'm quite enjoying it.
P.S.
I turn off aging so I can fully develop their stories. I decide when my Sims age up.