I do a few things to try and keep my family interesting. I usually play on normal speed so that they grow at a relatively good speed and I can move onto another generation as they get older.
- I setup the community lots in all the worlds before I start to play. I usually download lots from the gallery. I always have a library, gym/spa, bowling/arcade/roller rink (sometimes all in one, sometimes separate), restaurants, beach, vet office, wedding park or chapel, pub (for poker, foosball, darts and ping pong), bar and public pool. Parks always get upgraded to include swings and toddler play structure / slide. I also sometimes have internet cafes, ice cream restaurant, cinemas (although I find they don't function that well), dog and/or cat park, kids center, community center, etc.
- I try to give all my Sims a story line, hobbies and interests so that they are each their own unique person.
- I ensure my Sims visit the community lots that fit them so that I'm not just playing within their home lot all the time. Kids like to visit the parks, beaches, pools, bowling/arcades etc. Teens like to visit beaches, bowling/arcade, community center, diners, etc. Adults like to visit community lots that suit the hobbies and interests I've given them.
- I use the get together club system to create groups of friends. So that my Sims can go to the community lots and hang out with their friends.
- I don't always get my Sims to the top of their careers. I like playing average families for the most part so I usually pick a job for them and they only get to that level. That way there is more of a challenge because they don't have a ridiculous amount of simoleons.
- I sometimes get bored of the game I'm playing so I always have a few saves on the go and each are different in their own way. I have a rotational save, a single family save, a save where I play rotationally but only within the family, etc.
These are just some ways I keep my game interesting - they won't be for everyone but they work for me.