A possible mechanic for a long term goal/statistic/trend for the player is the idea of an Alignment. This differs from Reputation (though, I would have liked for the terms to be swapped around, since "reputation" fits this better), in that Alignment is not relative; it's your personal attitude, public reputation, and global appearance. Alignment would describe not your friends and enemies but how the sector itself treats you.
A starting character would have no alignment: a nobody. As time goes on, your character's actions and choices would contribute to alignment, growing the character's reputation in one way or another. This is what would separate a peacekeeping, world-saving industrial magnate and a ruthless military commander who considers happiness to be the lamentations of the women whose mates they slaughtered in glorious battle.
No doubt you already plan for most of these choices to be in the game. What this mechanic would do is present the player a tangible indication of what kind of person they've become, and what the public thinks of them. Strong descriptive words would be useful: Thug, Guardian, Dictator, Made Man, etc. would show not only the nature but also the magnitude of your alignment.
Because of this, it can tie in to campaign mechanics. Certain missions would only be readily available to certain types of commanders; other types of commanders would have look further or try harder to get work that they are not "suited" for. Some officers would only work for certain types of leaders, leaving if you strayed too far in a direction they don't agree with. Fleets might be more willing to surrender to someone who is not a known butcher, someone willing to let a crippled enemy go; if you don't take prisoners, nobody will leave you any.
Something to consider for facilitating content development later on, I suppose.