I had some thoughts for structures to distinguish the more industrialised planets from the mostly- empty systems with a golan or two. Any use?
Material storage platform- increases production speed (materials brought and stored close to the factory, etc), but is extremely weak to due storage of volatile materials. Can be built in space or on land.
Sensors stations. Provides an instant view of the area to a defender. No need to scout!
Era 3: Only available at Byss: Hunter-Killer Probots.
http://starwars.wikia.com/wiki/Hunter-Killer_probotModerately armed capital-ship sized droid that can pin anything up to even star destroyers in place with its tractor beam (it's main usage). Is mobile but is only built as a structure.