@Clousinators Here's the phone call that results in sims having a baby. This was the first time I got the call, so I'm not sure what the requirements are. I think sims need to be in a relationship, and I know that Lilliana has the Big Happy Family Aspiration.
https://live.staticflickr.com/65535/51489461490_352a7cfb6e_h.jpgThe response if you give the go ahead.
https://live.staticflickr.com/65535/51489461485_79c49e94e9_h.jpgOut of curiosity I confirmed that the pregnancy does happen.
https://live.staticflickr.com/65535/51488531376_ab62824cc3_h.jpgDuring this rotation, Whitley was a Doctor, so I can confirm that the Pregnant sim will not go to the hospital to deliver the baby. I felt like that was a disappointment. Whitley and Jason, from the rotation, are essentially the God Parents at this point. It would have been so cool if Whitley delivered the baby.
https://live.staticflickr.com/65535/51489242424_f32f7d4192_h.jpgPrank Phone calls also have interesting affects. I created an Evil Duo of my Favorite Twins. One of Evil Twins called and it actually helped with the bills.
https://live.staticflickr.com/65535/51210855875_5f3735db2d_b.jpghttps://live.staticflickr.com/65535/51209792641_8a09985cf9_n.jpgThe Prank Call about Vinny also has an interesting result. I'm putting it in a spoiler just in case someone hasn't experienced it yet and doesn't want the surprise ruined.
Rotation also let's you see your sims behave in unique ways. Dylan likes almost all instruments, so he will autonomously pull out a violin or guitar and play it. He has the skills maxed, so he plays exceptionally well. Sims will use items you leave in their inventory and use objects in the world like an Easel to paint. My sims like to help with the gardening.
https://live.staticflickr.com/65535/51240944340_3fc5fd8e14_b.jpghttps://live.staticflickr.com/65535/51239182587_2ab35107ef_b.jpgDylan and Zeph are master anglers, so they often visit fishing spots. If you give your sims certain skills, they will use them.
https://live.staticflickr.com/65535/51225670703_78308ec568_h.jpghttps://live.staticflickr.com/65535/51488532691_18e26b30ce_h.jpghttps://live.staticflickr.com/65535/51488752593_a81a6105e7_h.jpgRotation sims will show up at the vet if they have a Cat or Dog. I think someone from the "What Happened in Your Game?" Thread used it to set up a relationship for story purposes. If you like telling stories, you can use little details to increase the chances of sims interacting organically when you want to arrange a relationship.
https://live.staticflickr.com/65535/51407712345_97c2db347b_b.jpgCreative Sims will similarly act as entertainers and visit the Art District in San Myshuno to sell artwork.
https://live.staticflickr.com/65535/51538214679_bf03fe06fc_h.jpghttps://live.staticflickr.com/65535/51488751373_c51fca9b81_h.jpghttps://live.staticflickr.com/65535/51487742082_25f93adbcb_h.jpgSims that can play instruments can sometimes be the entertainers at City Festivals. There are phone calls you get to see them perform.
https://live.staticflickr.com/65535/51538418255_a677bd7371_h.jpgSometimes, sims will act completely out of character and do weird stuff. Kylen is not an Anti-Environmentalist or an evil sim. Everyone knows he's good because of his reputation. Still, he had a moment. lol. Sometimes we all need a snickers.
https://live.staticflickr.com/65535/51537490936_9622953549_h.jpgThis is Arihi, Dylan's Mom, and Dylan's Girlfriend when I realized they had a bad relationship. I wish I knew what got them to hate each other, but it definitely didn't happen while I played the household.
https://live.staticflickr.com/65535/51159962934_d35b0e547d_c.jpghttps://live.staticflickr.com/65535/51160285320_50631866d3_b.jpg