So many great types of lots and objects were added with expansion packs. University added bowling alleys and comic book shops, for example, while ambitions added consignment shops and laundromats. Plus there are some great venues from the store such as the stone's throw greenhouse, the ballet studio and the prism art studio. To prevent boredom in my current save, I took advantage of all the objects and lots available to me. In Fern and Preston's town, I added in a pizzeria, a sushi restaurant, a cat cafe, an amusement park, a driving range, a campground and a farmer's market, just to name a few. I can't build from scratch very well, so most of the lots were built by other simmers and downloaded from the exchange. I then proceeded to edit them beyond recognition. I've saved them for use in future towns as well. It was a lot of fun to do and it's a lot of fun to visit those lots! I'm excited to take my simmies out on the town to enjoy all the lovely things I've set out for them.
So if your town feels boring, my advice is to think about what sort of fun lots you could add to spruce it up. You could also edit existing lots, like adding a children's play area to the library for example. There are some amazing custom objects (like a ferris wheel) and fixes/improvements for broken objects (like the canning station and tea set) available at mod the sims and around the sims 3, if you're ever looking for custom content. Oh! also there are some custom jobs at missy hissy's website. It's fun to go on a 'shopping spree' on those websites, and I've found so many custom objects and interactions there that add more choices to my game.
As for game play, I like to have my sims work towards their lifetime wishes and jobs. Fern's lifetime wish is the animal rescuer, so she's going to adopt six pets (over the course of her lifetime so we don't get overrun by animals :P) and spent quite a bit of time bonding with them. She's just graduated from Sims University and is ready to start a cc career as a veterinarian. Her boyfriend, Preston, also graduated from Sims University and will be starting as a lifeguard. His lifetime wish is the seaside saviour one, so he wants to save lots of people from drowning.
Additionally, I try to have my sims make at least one lifelong friend and regularly meet up with them to hang out. I've got the seasons expansion pack so celebrating the different seasons adds regular fun to the game. I also try to make my sims act according to their personality. Preston's a party animal so that means regular parties and he loves the outdoors so that means most of his outings will involve being outside. I also try to give them hobbies according to their personality. Preston likes to scuba dive, surf and spend time with their dog. Fern likes to take care of this one strawberry plant and make jam with those strawberries, spend time with animals and because she's a hopeless romantic, she likes to read romance novels and I think that one day she will write a romance novel, as well.
Also it can be fun to have a story in mind. Mine is simple: a miracle romance. I want Fern and Preston to be a happy couple together because they are the founders of a legacy. There will be more drama-filled story lines down the line hopefully. Lastly, try challenges!