I've been hesitating to comment because I don't really do any of the creative activities listed. I find building a chore whose main purpose is to streamline my sims' functionality, and CAS is only fun when I'm attached to the sims I'm working on, like teens or YAs that I raised myself and whose recent birthdays have made them... less than presentable. Similarly, I only make changes to other lots when I'm about to buy one of the *spare* kids a house so that kid and family can move out, and even then I just take a premade house and add as many fun things to do as will fit on the lot. I guess I could say that I write stories in my head... but they're just for me, and no words ever hit the "paper."
Really, I'm just not the creative type.
But one thing I do enjoy is finding ways to make my sims more efficient or productive. To "hack" the game, in a way, but without doing anything resembling writing or modifying code. For example, I discovered how to use a game of tag to my advantage purely by accident, and now all my sim families have maxed out relationships with each other. Starting a new game with a sim family became much easier (including having a baby right away where I would still get to pick the traits) when I designated the founding couple as "engaged" and had them get married immediately. Discovering little things like these is what makes me happiest, and it's as close to creative as I'm likely to get.
