Putting that aside, as its not something people will easily change views on either way, in terms of differences to A New Hope, I agree one of the key set piece changes would be to the duel on the death star. I can see it playing out as the heroes are being pursued by a group of storm troopers, and Obi Wan stops to buy them time, and takes down a dozen troopers in a balletic flurry of sword strokes, feints, dodges and spins, before being confronted with Vader. They circle each other warily, watching for weakness, vader calling obi wan a traitor, obi wan calling vader a disappointment who chose power over honour. More storm troopers arive, and seeing no way to escape, Obi Wan smiles, asking if vader means to torture him. Vader strikes him down, a last act of respect to his old master. Maybe, givent he changes, the last kindness of a son to a father?
They escape, Luke distraught at hteloss of this newfound father figure, and seek out the rebellion. the film goes much as OTL, but as they attack the death star, lukes squadron is ambushed by an overwhelming force of tie fighters. his wingmen destroyed, luke dodges and weaves but the blaster fire comes closer and closer... until the falcon swoops in, smashing straight throught he imprial squadron, destroying them. witht he falcon as his wingman, luke makes his run, but the falcon is ablaze and malfunctioning. Han radios luke to tell him to do it, for freedom, for obi wan, fore leia, then flies stright into the defensive turret barrignt he way. the falcon explodes, and luke is temporarily in a panic, but then, remembering obi wan, he calms himself,breathing slowly, centring himself. he fires, and the missiles go intot he vents.
the next film is obviously now radically different. if lando remains, he takes han's place, btu is even mroe disreputable and mildly sleazy than Han OTL. the film follows the first films beats - the rogueish black sidekick who seemingly betrays the heroes but changes allegiance at hte last minute. At the end, he is captured by gangesters in league with the empire, and dies refusing to give up the heroes. Luke meanwhile seeks out the Yoda figure, who is now possibly human, if there is a suitable older japanese actor to play an archetypal wise sensei. instead of a swamp, he is in a part ruined temple amidst overgrown terraced fields. He teaches him focus, to control and channel his emotions, the importance of balance. Leia reveals that her father, who is alive here, is the true emperor, in hiding after he was deposed by the pretender, his brother.
ROTJ focusses on Luke seeking out his master's killer to avenge him, and to restore order tot he universe. as he is now not his dad, there is no need for him to change allegiance at the end, so their climactic duel comes as vader bars the way to the emperor's throne room aboard the new death star; their duel is long ad tense, but at the end, vader, realising how he has lost his honour and dignity, takes off his helmet, and kneels, asking Luke to do him the honour of ending his life for him. He obliges. Int he throne room, the emperor is a sort of dark version of human yoda. he tries to manipulate luke, bribe him, offer him influence and, for a moment, luke considers it, but closing his eyes, remembers his fallen master. he tells the emperor to stand down, and the emperor laughs; with a wave of his hand, his guards appear from hiding but luke, his eyes shut, focusses ont heir sound and the feel of the air and the vibrations ont he floor and dispatches them all in a single long movement. he stands before the emperor, and once more calls on him to surrender. the emperor pulls out a light staff, and they battle once more, but the emperor's rage is no match fo luke's calm, and he falls. witht he emperoro dead, luke deactivates the force field on the death star; leia tells him over hte radio she lvoes him, and begs him not to destroy himself witht he death star. he is resigned to it,however; until R2 chirps; 3PO, translating, tells himt here is an imperial escape pod hidden int he throne room, and he escapes just as the death star is destroyed, and rejoins the rebels. he and lei embrace, ad her father,t he true emperor, places herhand in lukes, and declares him his heir.