I haven't read the entire thread, so, I apologize if this concept was previously presented here, or in the countless EU fiction that's been written over the years.
I think it would be interesting to see something involving Alderaan. I don't mean to just show the planet in passing, but to make it a very important, prominently featured locale, in the same vain as Tatooine in SW. The main character could be a young Alderaanian (I don't know if that's the correct term), who grows up hearing about the powerful things the Empire can do, and, since the system is mostly out of their jurisdiction, he glorifies what is said about their staggering strength. Over time, we see him become a prominent Imperial figure, and truly strives to build a massive Empire. The film ends with Alderaan's destruction, as he watches those that share his ideologies obliterate his entire past. We could see the frantic panic of the citizens as this ominous space station draws nearer to their home.
If the movie ends here, it could lead to some uncertainty, or it could move onward to show him trying to create a fairer, modified, Empire, similar to the differing branches of Christianity. The Empire wouldn't take too kindly to this, and would brand him a traitor. This is NOT the Alliance that he's joined, but something totally different. Why does everything need to be the Rebels versus the Empire? Let's see the third parties.
Besides, it could really create a much more emotional reaction when the planet is demolished, which would leave a huge impact on the viewer, and, in a way, make the original film much more emotionally satisfying when you see it happen again, from Leia's perspective.