I put in Anything Goes, because the way I play each of my save files slightly different. I have 5-6 save files, where two are the most similar, and a newer one is following the pattern of another save file.
I have one save file where I am making families I made in Sims 2 into Sims 4 versions of them. 2 of the three families so far are Mages.
Two save files have my Sims, and a mixture of Sims based on smaller series I like. One save file has my Sims with Legolas from Lord of the Rings living in them, and some other Lord of the Rings characters, like his dad and Aragon. Another one has my Sims with a bunch of versions of Natsume from Natsume's book of Friends. Most of the series Sims like Legolas and Natsume came from the Gallery.
One save file has two sisters, and their families, and one sister is a mage with her own children. I moved the mage sister and her kids out, and had her have a daughter with a sim I took from the gallery. The sisters are in the same career, but the mage sister is doing better than her sister. The regular sister had a son born in-game, but I made her two children the same age as her niece and nephew. Except for the mage sister and her mage kids, the save file is pretty normal.
I have a "Frozen" save file, where I came up with different versions of the sisters. I have families where Iduna and Agnarr have Elsa and Anna as kids, and as teens. Another where Anna is married to Kristoff, and I gave them two kids to start with. There were at least two families like this, and Elsa lived with both. Another family I have has Agnarr and Iduna still alive as grandparents to Anna and Kristoff's kids. I also have one family where Agnarr and Iduna are still the same, but Elsa and Anna are boys. I threw in two families I created, which were the same family, but on my PS4 they had a daughter and in the other the had a son, so I moved the son version into my PS4 so the two versions lived in the same world.
My newest save file is Harry Potter, and it is going to end up fairly similar to the Frozen version. So far, I have the Weasleys, where Ron is a toddler, so I can get Ginny born in-game. I also have Harry as a toddler, but with his parents and aunt, uncle, and cousin. I have Hermione as a toddler, and plan to make her a mage when she is a teen.
Most of my game play is based on what would keep me entertained for a long time. It is pretty entertaining to see different versions of the same Sims interacting with each other. So, all and all, I tend to come up with an idea and wing it.