1. I have all kinds of rules for keeping my aging together and making sure I have variety. I currently move shortly after 2 am on Monday morning (after any Sunday holidays end and before the plants are available for harvest, and also very few careers ever work across the 2 am hour). I do Monday so that if my sims who are seeking fame have created anything that week they can attend the Starlight Accolades Sunday night. When I get University I may change the time to Monday afternoon for at least some of my households, because I think I want to run my terms Tues-Mon so they always get a weekend to either recover from a tough week or catch up if they're behind. I understand you have to rotate right before term ends to get credit for all the work you did and not choose between re-enroll right away or lose your scholarships. Each family is assigned a specific pack or couple of packs that is their focus so I don't get stuck in a rut doing everything the same and so that I can eventually use all the content I have purchased.
I have a retirement village and any time a teen/child/toddler premade grows up with and marries my sims, their parents move there as elders so they don't live forever. Other than that premades and townies don't age unless they become important to one of my sims, and then they get aged manually with the sim they are attached to and move to the retirement village when they hit the elder stage.
One week for each family, and by the end of each rotation I write out the order I want to play them in next, based on which holidays or seasons I want to do with which household. I sometimes change that as I go, but only with the households that haven't had their turn yet so they all age the same amount each rotation. I play with aging off except for the active household.
2. I started this save with a single sim with the Serial Romantic aspiration. She had nine children with five different fathers, so as they grew up and moved out it grew to 9 households. Then I only let the next generation have one pregnancy each (with one exception) and where there were twins I created/will create new households with the spares. That will eventually create 4 more households, though they aren't all grown yet. And then I created a few additional occult households for more story-based play.
3. It's the only kind of play that holds my interest for more than a month or so at a time. And when I do walk away from the game for a while, this is the save I am attached to and return to. I never played Sims2 any other way.
4. I have at least one household in every world, except a couple where I'm waiting for the founder to get old enough to move there. Newcrest is mostly commercial, but does house my ghost household and eventually will also house the aliens and the robots.
5. My sims age very slowly between the number of households I play and the breaks I take for the game. So the part of me that would like to watch generations go by gets frustrated sometimes.
6. I like family and occult play, and also occult family play. That's why I have a separate household for each occult, in addition to vampire and spellcaster branches of the family, so I can do all three within the same save. I raised the aliens born in my families, but as adults they moved in together and made an occult household. My only mermaid is not part of the family, but is related to the non-family vampire storyline. I also have a house of premades killed by my vampires and now haunting a house together with a Patchy servant. But I love multi-generational family play so that is at the core of this save.