Well, the logical place to start for a campaign would be SC1. The first mission[besides the needed training for this] would probably be the Terrans trying to halt the Protoss bombardment of Chau and Mar Sara[I would assume there would be local resistance]. Protoss do have beams for bombardment from orbit[aka 'Purifiaction]. The Terrans obuviously would be forced to retreat.

The later battles would continue to follow the story, such as more orbital battles against protoss and platform/land battles against protoss/zerg
An interesting idea I had was to have the campaign played from all three viewpoints, such has the Protoss defending the space above Aiur. However, there is a modest lack of information about SC space battles, so much would have to be story based conjecture.
As far as ideas for models, Protoss ships would primiarly have fighters for defense, but
very strong shields. Could also use beams/missles. Terrans would primiarlly use rapid fire lasers for fighter defense [new rapid fire weapon model likely needed], and larger lasers[battlecruiser yamato and smaller anti-cap batteries] as well as nuke missles[hypothetical, but logical and fits, as long as tactical type]. Zerg would primiarly use, well I don't know what you would call their bio-weapons. Lots o new weapon models needed there.
That's all I want to type for now. Good luck digesting it
