SimCity does have an answer to complaints about the city size limit. It's imperfect—I'd rather be able to build bigger cities—but it's a decent solution: I can approximate my urban planning ambitions with multiple cities in the same region. Because they can interact by buying and selling resources to each other, I can build symbiotic cities, each with its own job and personality. One might be dedicated to suburban sprawl, another to industry, another to tourism, and so on. I didn't have time to test this fully, but it's clearly the idea behind region play.
Above is my second city. My plan, which I didn't have time to see through, was to build a bustling commerce city with high-wealth residents who might want to drop by Port Foozle now and then to play some craps or go clubbing. As you can see, my plan was also to make lots and lots of curvy roads. I love those curvy roads.