After browsing websites, reading emails, and sifting through some of my neighborhoods, I created a list of themes for neighborhoods. So if you are looking for something new to do with your Sims, or aren't feeling very creative, try one of the themes I've listed below to get you started.
TV Shows/Movies
Creating a neighborhood based on your favorite TV shows or movies can result in some very interesting situations. If you have watched a particular show enough, you should be able to come up with the basic layout pretty easily.
Single Sims
This is especially fun if you have the "Hot Date Expansion Pack." Create a mixture of males and females, and have them meet each other Downtown and hopefully fall in love. This type of neighborhood can still be fun even if you don't have "Hot Date."
Large Families
Make families with lots of kids, with one or two parents. Kids are also good for adding family friends. This is useful if you are trying to earn a high-ranking job. Sim kids sure can be brats sometimes, so only do this one if you are up for a challenge.
No Cheats
Everyone should have a neighborhood of poor, hard working Sims. It's so much easier to just use the money cheat, and build them lavish homes. Well, its time we make those Sims earn luxury homes! Try to earn money and friends the honest way, by not using any cheats.
Party Homes
If you have "House Party" you've probably already created at least a couple houses devoted to have a good time. If you don't have "House Party" this theme may be a harder, since you won't have the objects available in the expansion pack.
Trailer Parks & Apartments
Build a couple mobile homes on a lot. It can be hard to get the families to stay in their own homes. I suggest on making one kitchen, so your Sims aren't cooking 3 different meals for the same meal.
Rich Sims
Build large homes and decorate them with expensive furniture and paintings. Of course you'll have to use the rosebud cheat to properly decorate for wealthy Sims.
Victorian Homes
Victorian style homes are popular among Sim sites that offer homes. So if you don't want to build the houses, but like to decorate, downloading them is a good option.
Real Life Families
I bet one of the first families you made included yourself and either friends or family. Why not make a neighborhood entirely of your family? The situations that arise are usually quite funny. It can be hard to keep the Sims from falling in love with people they shouldn't be!
Winter Wonderland
Once winter comes, it just makes sense to create a neighborhood full of snow. There are plenty of snowy objects you can download from fan sites. Just look around, and you'll find some great stuff, including snowmen!
Holidays
Let your Sims celebrate your favorite holidays with you! In "Living Large" Maxis included some holiday objects, but you can find much more on fan sites.
Tropical
Put that Tiki set Maxis created in "House Party" to good use! Create a tropical paradise for your Sims. A few fan sites have extended the set by creating objects that match! 7 Deadly Sims a great selection of Tiki objects.
Farms
Send your Sims to the country! Just don't let the animals take over!
Log Cabins
The wilderness is a place to reflect on your life. Sims all need a little down time as well. Give them a vacation, and build log cabins so they too can get away from the stresses of life.
Rainbow
Give each lot a specific color, and only use objects of that color. You shouldn't have any problem finding recolors of Maxis objects on fan sites. This would be a fun project for any addicted Sim fan.
Castles
The "Living Large Expansion Pack" has objects that will help you build a castle. Many of the objects in "Living Large" have a fantasy theme to them.