Here's an idea to add strategy, make the galaxy more interesting (not to forget pretty) and be fitting

Nebulaes or Space clouds (so to speak) on the map.

The thing nebulaes brings to the game would then be something in the lines of:

Safe heavens for ships:
Nebulaes could emit radiation and such effects to force you to research "endurance" technologies to endure long stays in them, or perhaps to be allowed to even enter them in the first place without loosing you ships.
Perhaps they could have varying effects and varying "thicknesses".

Hiding places
Nebulaes could then also be used for launching Assaults or similar on passers by. Thus fulfilling the "forest" type of cover we see in land based games.

Creating Obstacles
An unpenetrable nebulae could even be used to force the players to take certain routes to go around it. In effect creating more interesting "maps" of the universe.
Thus bringing in the "mountains" element from land based games as well.

These land based comparisons are just for ... comparison, to clearer clarify the point of having the feature.

Anyway having a nebulae stretching half the map forcing all AI to take even more into account while it brings beauty, strategy and diversity <--- my salespitch.. would be neat.

This is actually somewhat of a repost I apologise for that, I posted this in a insanely huge thread somewhere in this forum. Then found "Game Ideas" which seems more fitting