I think a newspaper company would be an interesting addition because it would introduce a completely different type of business.
The player could build a newspaper office and hire journalists, editors, photographers, designers and delivery workers.
Newspapers could be produced and distributed throughout the city.
The business could grow based on its reputation and readership.
Possible gameplay:
Journalists → Gather News → Newspaper Production → Distribution → Customers → Revenue
It could also react to major events happening in the city, making the world feel more alive.
Eventually, the player could expand from a small local newspaper into a large publishing company.