For me, the most difficult part of SimCity 4 has been coming to grips with the notion that growth can require a disruption to a stable equilibrium. You have to take something that works, break it in some small, but definable way, and then pour effort into fixing the bigger, better, but broken thing that emerges in the aftermath.
There's probably some important life lesson about risk and growth in there somewhere, but I'm not sure I want to hear it. I'm just generally pretty risk-averse and I like it when whole things stay whole.
That said, I think I've more or less figured out the city-management aspect of the game. I've been able to keep a balanced budget, get all of my public opinion bars up to maximum, and deliver adequate civic services. The one thing that still hangs me up is traffic management. There's so many options, and I can't really get a handle on the strengths and weaknesses of each. I like to think this is subtly educational, and that by getting good at the game, I may learn a thing or two about how real cities manage traffic, but I've not seen any evidence that SimCity is particularly realistic in this regard.
I also think I might be getting the hang of this regional play thing. My current city has 50,000+ people, and almost no industry, thanks to being adjacent to a highly industrial city to which my sims can commute.
I don't know if I have any special goals for the last half of the game. Try to keep things on an even keel. Hopefully reach 100,000 people in a single city map. Maybe fill up a whole region. I'm not sure how ambitious these goals are. The last, especially, feels more tedious than difficult, and would probably take more than 10 hours besides, but I'm almost certain I can reach 100k citizens.
My feeling at this point is that SimCity 4 is a game that rewards a light touch. If you have a willingness to sit back and let things happen, you'll get better results than if you're constantly fiddling with the controls, trying to squeeze out greater moment-to-moment advantage. Although, that could just be my inexperience talking. Maybe there is a way to micromanage your cities and have them grow super fast. However, if there is, I'm unlikely to discover it in my remaining time.
So, almost by default, it's slow and steady for me.