It wouldn't hurt to put a preference in there somewhere and let people determine how much randomness they want.

You'd have to adjust your combat program to make it so that ships on the same team won't damage each other. When two allied players simultaneously attack a planet, they'll work together to defeat the enemy if there is one, and then the player with the largest fleet takes the planet.

Afterwards, or if a player attacks a planet owned by an ally, the fleet will either return to its origin, or it will return to the nearest planet which it owns.

Just a thought, since I don't know what the current options are for the game it may or may not apply, but it would be neat to be able to generate a map with a solar system setup, where there's optionally a noninteractive star at the center, and a number of large planets generated in the general vicinity of the star. Then a number of smaller planets (moons) generated around each large planet. That'd create an interesting set of clusters, plus a 'struggle for the large planet' effect in each cluster.

Also, while playing the game, I question whether it might be a good idea to multiply the bonuses of large planets instead of just increasing the base production.
So instead of:
   Small: 3/6/9/12
   Large: 5/8/11/14
It might be:
   Small: 3/6/9/12
   Large: 5/10/15/20

That would make large planets much more desirable all throughout the game, instead of just at the very beginning.

Just some thoughts.