I really like to see an scenario editor, would be perfect for Role-playing.
And offcourse Tactical-ground combat, better ground combat in general !!
Yes wait, also orbitting planets around the system star or centre. Would be perfect every time you enter a system the planets are somewhere else..
the possibility to let your population life in space would also be good (space station colonies or something like that)
I better stop now !!
Intimidator