Well, I'd probably have gone with what Gary Kurtz had in mind.
Gary Kurtz:
One of the reasons Jedi came out the way it did was because the story outline of how Jedi was going to be seemed to get tossed out, and one of the reasons I was really unhappy was the fact that all of the carefully constructed story structure of characters and things that we did in Empire was going to carry over into Jedi. The resolution of that film was going to be quite bittersweet, with Han Solo being killed, and the princess having to take over as queen of what remained of her people, leaving everybody else. In effect, Luke was left on his own. None of that happened, of course.
It would have been quite sad, and poignant and upbeat at the same time, because they would have won a battle. But the idea of another attack on another Death Star wasn't there at all ... it was a rehash of Star Wars, with better visual effects. And there were no Ewoks ... it was just entirely different. It was much more adult and straightforward, the story.
There's a lot of undercurrent in Star Wars that, if you take it on the surface, a four-year-old can really enjoy it – but there's a lot else going on, under there. In that sense it's multi-layered, and Empire is as well. That's the thing that bothered me a bit about Jedi and certainly about Episode I, is that those layers, those subtexts – they're all gone. They're not there. You accept what's there on the screen – it either works for you as a surface adventure, or it doesn't. But that's all there is. There's nothing to ponder.
Given that we can never get our hands on Kurtz's version of Jedi, though, I'd probably do a version which attempts to live up to his ideas while still using that which is good from the original.
The film would open with the Imperial Planet - a very dark industrial world with the Imperial Palace dominating the skyline. Though we would not see his face until the end of the film (except for a few statues which litter the palace's interior), the Emperor would berate Vader for his failure to capture Skywalker. Vader would play the humble servant, though it would be made clear that he is still plotting against the Emperor. These sequences would be based on unused concept art created by Ralph McQuarrie. I'm sure you've all seen it.
http://lostepisodes.fateback.com/graphics/pictures/conceptart-coruscant1.jpg
http://www.theforce.net/episode2/newspics/rmq-coruscant3.jpg
http://lostepisodes.fateback.com/graphics/pictures/conceptart-coruscant2.jpg
http://www.theforce.net/swtc/Pix/books/art/coruscant1.jpg
Luke's discussion with Yoda, and the build up to their discussion, would be quite different. Rather than simply appear in Yoda's hut for a conversation, Luke would discover his home in disarray and the fragile Yoda in a rapidly deteriorating state. He would light a single torch and begin their conversation, in which Yoda reveals that Vader is indeed his father. Yoda would mention that there is yet hope not just for the Rebellion but for Luke's father, the "other" trapped in the twisted mind of Vader. After Yoda dies and fades away, Luke would look forlornly around the lonely hut and say to himself that he "cannot go on alone".
The disembodied voice of Obi-Wan would respond with "Yoda will always be with you". Coaxed out by the voice, Luke would enter the swamp and see the spirit of Obi-Wan hovering over the water. I always felt that having Obi-Wan sit down for a one-to-one with Luke robbed him of his spiritual mystery. By placing a physical barrier between Luke and the ghost of Obi-Wan, we can emphasise their separateness.
Rather than offer the incredible explanation of "points of view", Obi-Wan would simply admit that he had lied. "When I first knew you, Luke, you were a young man desperate for guidance. I feared that if you knew your father's fate, you would follow him along the dark path. I don't expect you to forgive what I did, but, please, understand it." After Obi-Wan encourages him to defeat Vader, ignoring Yoda's belief that there may yet be hope for him, he would state that he has already overstayed his time in the realm of the living and begin to fade from existence, offering Luke some parting words of advice. Desperate, Luke would hurry to the fading image, even partially submerging himself in the marsh water. However, the ghost would finally fade, leaving Luke to decide his destiny alone.
The impressive puppet of Jabba the Hutt would be kept, though many of the other puppets would be replaced with more credible alien models, some based on more complete versions of the simple masks which appeared in the first film. The pig-like Gamoreans always bothered me. In some of the Rancor concept art, they appear as slightly Orcish creatures. This is the version I'd go with.
http://www.df.lth.se/~ola/Starwars/Return/images/return6.jpg
I'd keep some of the more iconic images from these scenes - bikini, carbonite reveal, Rancor etc. - though I'd remove the failings, such as Salicious Crumb, the death of Boba Fett and the extremely flawed rescue plot.
The finale of the movie would feature an assault on the Imperial Planet. The Rebels reason that the Emperor's increasing centralisation of power (as we hear of in Star Wars, with the dissolution of the senate) is simply part of his authoritarian style, but there's another element to it. All along, the Emperor has been coaxing the Rebels to attempt an assault on his planet, which houses more and more of all the effective members of government. Centralising power was both about control and deliberately placing a target on his head. His plan comes to fruition when details are "leaked" to the Rebels about the present location of the Imperial fleet, which is spread out desperately searching for them. The Rebels calculate that an assault on the palace could be successful before the Imperial Navy could ever descend on them or take notice of the attack. Of course, it's all a trap.
What the Emperor does not count on, however, is that the populace of the Imperial Planet are preparing to turn on him. The oppressed aliens of the lower reaches of the city, who the heroes encounter, prepare for a violent insurrection against the Imperial military at the request of Leia. The aliens include a group of Wookiees, and we learn a little of Han's relationship with Chewbacca, and how Han had initially been an Imperial recruit. After witnessing the brutal repression of aliens first hand, Han defected and started a life of crime. This revelation is difficult for Leia, of course, who has devoted her life to opposing the Empire and its agents. Discovering that Han is not merely a "scoundrel" but possibly a former participant in Imperial crimes drives a wedge between the two.
Driven by a newly awoken sense of guilt, Han throws himself into the battle with reckless passion. In the chaos that follows, the explosive charges for destroying the planetary deflector shield are damaged and can only be rigged manually. Han must choose between self-preservation or sacrificing himself for the cause of the Rebellion. In this moment, the differences between Leia and Han are reconciled. Leia initially prepares to rig the charges herself, but Han inists that Chewbacca bring her to a safe distance while he does the job himself. In this way, Han truly makes the transition from the-guy-who-shot-first to a martyr for the cause of freedom. Obviously it takes on a far more personal dimension, as it could be said that it was more his love of Leia that drove him to perform the necessary sacrifice.
Vader is similarly overcome by his better impulses and destroys the Emperor just as he is about to kill Luke. The redeemed Vader shares a final moment with his son before dying, as in the original. The Rebels infiltrate the planet, fire at the palace reactor and destroy the Imperial Palace. Luke escapes in an Imperial shuttle which passes into Rebel held territory under heavy watch. After a moment of tension, Luke emerges carrying Vader's body. He is then permitted to cremate him. During the cremation Leia reveals Han's death to him and they embrace in front of the pyre.
Bearing the emotional scars of the battle they have endured, Leia and Luke are then comforted by the sight of the celebrating citizens who have risen up and won their freedom. Luke has passed beyond adolescence. Previously, Obi-Wan truly seemed like an infallible being, but now that Luke has reached the same level, he sees his failures, he sees that he was human too. He forgives him for having lied, but having witnessed Vader's redemption, he realises that the clear dichotomies Obi-Wan had offered him were inadequate. He develops his own sense of the Force, of himself and his potential. Leia, on the other hand, must turn away from the man she had loved and accept the burden of forming a new society. Luke, who has been touched most heavily of all by the conflict, cannot follow her on this new journey. They part ways and Luke heads off into the galaxy, to seek understanding and healing for himself.
Not exactly a typical Hollywood ending, but, hey, I think me and Kurtz would have liked it. Thinking about it, though, it'd probably have to be changed so that both Han and the Falcon are destroyed at once, because the two are so caught up with each other. To leave the Falcon lying around when Han is gone seems inappropriate. At least Chewie could form a connection with the Wookiees, the Falcon would simply be inherited by Lando, which would seem to add insult to injury for Han.
Phew. That post went on much longer than I intended. I applaud any person brave enough to plough through it all.