I was playing a mission the other day, and I was feeling like a terrible commander as I abandoned my destroyer, which was presently swarming with enemy fighters after I accidently got out of position, for one of my capitol ships. As my tiny shuttle pod flew across the battlefield to my capitol ship, I observed some epic battles going on throughout: fighters swarming destroyers, capitol ships going head to head, etc. I thought, how awesome would it be to observe and spectate these battles?
So here are my thoughts on how this could work: the "spectator" could just be a small ship, like the shuttle pod. Perhaps the animation for switching to spectator mode would be similar to the animation that occurs when one transfers command to another ship. The shuttle pod would be incapable of attacking, being attacked, colliding with other ships, being collided with, etc. and would have a top speed of 250 to 300, unaffected by nebulae. Perhaps the zoom out could be increased so that the field of vision is a bit bigger. Also, the spectator would have vision of the whole battlefield on the mini map (i.e. no fog of war).
Of course, the intelligence gained from this last bit could affect gameplay. In response to this, you could make it so that, if one chooses to go into spectator mode, one cannot go back to pilot any other craft, leaving the other ships to make decisions based on the AI. I think that one should still be able to execute commands on the mini map (you're still a commander after all), setting rally points and capturing objectives and such.
So if you run into a larger fleet that you know you can beat, and you like a good show, you can start the battle, switch on spectator mode, sit back and watch the destruction.