My Sims have to "pay" for new clothes and completely different hairstyles. E.g. they can tie a simple ponytail on their own of course, but if they want their hair cut shorter or dyed, they'll have to spend those $$$.
I have small headcanons on where the worlds are located.
For example, I imagine Willow Creek, Newcrest and Magnolia Promenade are quite close, so Sims can easily travel between those worlds in just a day. But if they want to go to, say, Sulani or even Oasis Springs, they'll have to invest a bit more time. Example: My Sim lives in Newcrest and is "invited to a job interview" for a position as Conservationist. It's all the way over on Sulani, though, as I think those two worlds are probably far apart. So my Sim has to pack up a day before and leave the house in the morning. Travelling to the islands takes a Sim day, so they aren't allowed to do anything on the day they go there to simulate that. Can't go swimming by midday if you've only left in the morning and travelling takes almost a day, yadda yadda.
On the note of job interviews: I like using a random generator to roll if my Sim will "get the job". Let's say my Sim wants to apply for a job as Mixologist. So they do, but instead of using the phone (since you'll get the job right away), I open the generator and roll for either "Got the job" or "Didn't get the job". Got the job? Congrats! If not, they can either apply for a different job or try again in a week or so. Sometimes I'll let them apply for the same one again, but if the second roll is successful, it's not the same company / place, so they might have to move since it's too far to travel between two worlds daily. Hope that explanation makes sense. ;
I do "opening hours" for certain venues as well. Parks are always open, but libraries, museums, nightclubs etc are not. I make up opening hours during which Sims may visit, and they cannot go there outside those hours. E.g. a library may be open from 10 AM to 6 PM, so once it's about 5:50 PM my Sim will have to get ready to leave for the day.
Something really small, but I never see anyone mention they do it: I always make sure my Sims brush their teeth in the morning and evening. :D
