Edit: Originally this post was about how to do this, but I read the "How to Play" again and figured it out.
Anyhow, great game. Someone buy the sound guy a beer for being awesome.
If you add functionality for selecting units, I recommend you add a slider to select "All Units but X". That way, I can leave a standing army of 5 or 10 units on planets in dangerous areas, while still moving the bulk to the front lines.
