I can say I've never really been that excited for SimCity games. It might have been the difficulty, or just that I didn't get them. After getting a brief glimpse at the new SimCity, slated to release in 2013, I actually can't wait to get my hands on it. It could be the fact that the gameplay looks more streamlined and accomodating to newer players, but even the integration of a seamless multi-player sounds super appealing.
Seamless multi-player works like this. Your city has neighboring regions that your friends and other players can join. Once their city is established, you help each other out, even without realizing it. For example if I build a strong police force, complete with a helipad, his city will benefit from police building and it will help prevent crime for both of us. Neighboring cities can even help each other power one another, or let one city focus on providing the power, while the other builds their city up into a metropolis.
Multi-city play looks to make SimCity even more fun and strategic to play with friends, rather than building a city on your own. Make sure to look out for SimCity in 2013.