Also maybe add some sort of smaller static objects? Like weapons platforms, mines, communication satellites, beacons/buoys and storage containers.
Maybe instead of building big and expensive stations in a sector in order to capture it, we could instead put down a comm satellite and a couple of weapons platforms combined with the occasional AI patrol and have those be a way of marking the territory of your faction. And as always have the player be able to change how those comsats/beacons/platforms look and work.
More on the topic of player territory, when a sector is under attack (especially when it's another player) it should appear something like this on the map.
Additionally it would be nice to give more info on how many ships there are on the attacking side or give the player the option to have more AI ships sent to that sector.