There are two ways I commonly break my cities:
Spending Money On Things Before Sims Want Them
Sims want things... schools, hospitals, parks... but they want some things more than others, and if you build them in the wrong order you are WASTING YOUR MONEY, because they don't have their full effect. On the quick reference guide, as well as buried deep in the Sim City Manual under the desirability chart, is possibly the most important information to the game that no one knows:
What (Sim City) Sims Want
Although you can’t directly affect the types of occupants that develop
in your city, you do have indirect control by affecting the desirability
of the zoned areas of your city. The following actions can be taken to
improve the desirability for each of these occupant types:
This chart is ORDERED. Residential Sims want police more than hospitals. Dirty/Manufacturing industry wants police, then shorter fright trips, then NOTHING else, they're happy. After you've taken care of the basics that every zone wants, power and water for higher density/$$$, take care of problems in this order and you'll spend less money, attract more Sims, and make more money. I'll repeat once more:
I think this is the most important info people are missing to building a great city.
Not Replacing Dying Utilites
The utilities buildings, water pumps, power plants, and incinerators age over time, more for the more they are used. They gradually cost more to maintain and have lower output. Eventually, you are paying out the nose for nothing. Replace them as soon as you can.
Special note, if you are using Waste To Energy incinerators, turn them down to producing no power and have them only dispose of waste. This prevents the plant from aging in any noticeable amount, and you can then buy your power from a cheaper plant. The downside is that your power budget will not be at 100%, so 1) new plants will start at whatever the budget is set to overall, and 2) there is a chance of fire on all power lines. So just don't use any... use low density commercial zone instead. Same power spread, no cost, possible income.
As far as I know, Windows emulation/installation on Macs is near perfect. Getting Windows on your Mac and then playing the Sim City's in that would be the best choice.
And for SC4, no matter how good your computer is, it's still going to lag. It was just poorly programmed for certain scaling tasks.
Best Answer
I've been playing SimCity 4 (Deluxe Edition) on Windows 7 64-bit for a few weeks now and it's been relatively problem-free. I did have a problem running the game full screen after installing the update available from EA, but right-clicking the shortcut, going to Properties → Compatibility, and checking the Disable desktop composition option resolved that issue.
Outside of that, the game has run fine. I haven't experienced the Alt+Tab issue that Buss described, so I'm unsure what may have caused that. I did install the game from the original CD, so the SC4 + Steam might be the culprit.