Re: What kind of storylines do you play in Sims 4?

I do a lot of sprawling rotations and one-off challenges.

I'm doing a lot of vet clinic/retail store type things (yes, you can do those things if you have Cats and Dogs for the vet clinic and Get to Work for the store) in this save, which is interesting. I try to include some things in the stores that I would like to buy as my other Sims (like the Realm of Magic tomes, and even some completed potions, and I'm going to give my florist the 30 mermadic kelps I found exploring the beach cave...).

I'm also really enjoying putting all my kids in all my households in a kids club, all my teens in a teens club, etc. That means that even when they're NPCs because I'm playing another household I can see them and hang out with them, and they gain skills and friendships when I'm not playing them!

[adding more specifics]

What I've been doing with my current save (and not for any one-off challenges or scenarios):

Mods: MC Command Center, UI Cheats, Wonderful Whims, Pregnancy and Relationship Overhaul (formerly Woohoo Wellness), Whim Overhaul, MissyHissy's Personality mod, KawaiiStacie's Education System, SNB bank. Aging is set to active household only. Risky woohoo is set to a flat 20%.

Set up starting households by:

• Giving them a Personality type based on their aspiration category. If the aspiration category doesn't have a corresponding type, roll a d6.This is optional but does give your Sims different whims from one another; one will want to open a business, another will want to adopt a dog or hamster, and a third will want to become a spellcaster and then get abducted by aliens. I use this with Bienchen's Whim Overhaul, because I've seen "buy a bee box" so many times that it now makes me irrationally angry. 😉
• Manually set sexual orientation with Wonderful Whims under attraction settings (for Maxis townies with a bio, you can use that, or your personal headcanon. When in doubt, or for future age-ups, I use a d100 and say 0-30 is gay, 70-100 is straight, and everyone else is bi unless I want them to be ace--you can, of course, set your own values).
• Look at the pregnancy wish Pregnancy and Relationship Overhaul assigned and if they don't want children they get birth control. That said, if they're family-oriented they always want children and if they hate children they never want children. Everyone else risks it. 😉 At least until they have 2, and then I cut them off. :P
• If the household is roommates, they get bank accounts for when/if they get married. Teens with part-time jobs can use bank accounts to save up for university and moving out on their own after.

Then I play, using their aspirations, their whims, their careers, and whatever other plans I had for this household to guide me. I play for exactly one week, Sunday to Sunday, and then move to the next household.  Repeat.

On age-ups, I use the Legacy Challenge trait generator, but I also hit refresh if I don't like that answer.  😉 I do this because I don't want to straight-up hit randomize but I also want to be encouraged to use traits or aspirations I wouldn't otherwise, and I like that the parents' traits have an influence. (Left to my own devices, every Sim will be Self-Assured, Good, and a Genius.) Also I get to avoid traits I find deeply annoying. At teen I assign personality type and sexual orientation; at young adult I check their pregnancy wishes.

All children start with the social aspiration and join my Kids club that meets at the park: Activities: be friendly, play with toys, play on playground equipment, do homework, play chess. Banned activities: be mean. Bonuses to all childhood skills, charisma, logic, and friendly socials. Because I'm very competitive I always want to make all my kids get top notch toddler and all 4 childhood aspirations if I can swing it. If they get a whim to "get a job" I flip a coin to decide whether they do drama club or scouts even though I prefer scouts because my competitive self hates to leave a bonus on the table.  😉

My teens all join the teen club that meets at the bowling alley. Activities: bowl, dance, be friendly, be funny. Banned activities: be mean. Bonuses to charisma, bowling, dancing, friendly socials, and romantic socials. I've had teens max bowling and dancing as NPCs and then attend university on a bowling scholarship!

If the family is poor, or the teen gets a whim, or I just think it suits them they might get a part-time job. They might also join or continue scouts or drama club.

If Wonderful Whims tells me they're really into someone (and that person doesn't have an orientation that prevents it) I'll try to get them together. This is part of why my bi percentage is so high. I also have a fairly high gay percentage because I want gay and lesbian couples in my game! That said, yes, my straight and bi women tell me they're super into the gay guy, and my straight and bi men tell me they're super into the lesbian, and I tell them sorry.

University: When someone ages up to young adult, I move them into a currently not in world household named either Britechester Students or Foxbury Students with $5K per Sim added to the community funds. They hang out in that household until the end of the rotation, and then they all move into an apartment together. I then turn aging off, and they apply to university, apply for scholarships, and work and do odd jobs. On Friday, I enroll them in University and endure loading screen purgatory to put them all in the same dorm. (Five students? Ten loading screens!) They also have a club with the activity "be friendly," but once they're in the dorms I add "do homework." That Friday, they all start their term papers and presentations and homework, front-loading as much of the semester as possible. Anyone who sleeps quits their part-time job (my vamps kept their barista jobs). Their majors are determined by their aspirations, their personalities, any lifestyles they've acquired, and their current skills. Upon graduation, they move onto an empty lot at least until the diplomas spawn, and then I put them all back in their original households (and I turn aging back on).

New graduates might end up getting a job other than the one that led them to pursue the degree. For example, one Sim who got a Biology degree because he had the body builder aspiration ended up becoming a Doctor. Another who pursued Economics because he was in Business ended up an Environmental Manager because he developed the Outdoorsy lifestyle studying at home and gardening to support his family. I LOVE this.

I personally leave aging and neighborhood stories off for townies except during aging week, which is the first household of the rotation. I want my townies to age as the same rate as my Sims.

And there you have it! more than you wanted to know.  😉