Once I scout a system, I want to be able to see the locaiton of where everything was.  Perhaps dim it out so its 100% clear that what you are looking at was the location of all of the ships and buidings the last time the system was scouted.

I don't like how when I look at a system that I don't have an active scout in, Its empty and I can't see the location of the buildings.  I might have sent a scout to look at some systems, but then I get distracted by a battle.  I still want to be able to see where that star base was in the system or those mines were without having to send in another scout.  That way I don't jump into a trap.