Do you rename Sims? Particularly non-played Sims?

Yes and no. In my main saved game I don't bother unless I have multiple Sims with the same last names (unrelated ones I mean) and the CL cultural names I don't mind much but I do edit them a bit if I find a Sim whose features don't really fit their game chosen name. I did change one Sim's name because his name was to much of a mouthful to fit his to soon to be famous standing. I wanted something 'normal' and catchy name for him. But I made sure to write down his former and well real name to make sure I wouldn't forget it for story purposes. Some of his children will keep his original last name.