http://foreignpolicy.com/2012/09/28/aircraft-carriers-in-space/
It always bothered me that space stations could have influence beyond a solar system, that any useful information could be had by long distance scans (other than historical), or that space battles could occur at all in deep space (good luck finding a fleet in a cubic light year of space).
The problem is distance and time. Our galaxy is 100k light years across and that's rather small on the average. Anything you can actually see is historical. which means any and all attacks are by surprise. Only sending something FTL and retrieving it will give reasonably current information.
Also, the energy cost of FTL and the need for exotic materials would make it rare perhaps requiring maybe at least a Kardashev II civilization.
This means that, to be somewhat reasonable, most of the game action should be developing the solar system with contact and conflict being rare but high risk.