I kinda agree with RIS Mace's ideas here with SFC1. Even though that game is arcaic compared to newer games and is hardly used compared to the later SFC's, it still is not a bad game, and perhaps some ideas could be based apon it.
SFC1's campaign ideas were very good in my opinion, and I really liked the variety of senarios the game offered compared to later SFC titles. And if SFC4 is going to improve campaign ideas, may I suggest two different types of Campaign maps? Perhaphs have your standard "Hex" based map like in SFC2, OP, and 3, but also have a choice to choose a map that is similar to the old SFC1 map. I kinda liked the old map because it sort of reminds me of the old "Risk" or "Diplomacy" board game maps. This might also help keep things simple for new players as the Hex Maps in SFC2 seemed a bit crowded to me.
And while were at it, it would be nice if you could actually setup "Real" campaigns for single or multiplayer games. What I mean by "real" is actually setup "Orders of Battles", Fleets through out the map for each empire (not just your personal Squadron, but able to edit all Fleets on the map!), modable construction schedules, set time frame a campaign/war lasts, Placement of Capitols/Bases and Resource Planets, If ships are allowed to be constrcuted like in SFC3 then have Technology Advancement, different types of Victory Conditions for a Campaign/War, etc. These are just a few ideas I would like to see, more options and enhancement of Campaigns.
And a final note. As much as many didn't like SFC3, I must admit the Hidden Cloak concept was a neat feature and should only be added to SFC4 as an "optional" rule. Not sure about the Warp feature in SFC3. In my experience in games, it got abused A LOT! I would vote no on that.