What should I put in my minecraft city?

Skyscrapers, roads, sewers, cars, a dock, an airport, if you have any mods you can do that stuff. If you want to make it like RP or something then you can use a mod (I forget which but it gives you played models and you can make npcs that look like characters and talk and stuff) to make these really cool jobs that they can give and you can earn money to get stuff. It's pretty sick, if I can find it then I'll post a link to it in the comments section of my answer.

McDonalds. Burger king. Wendy's. Jack in the Box. That's all you need