You've got a time machine, and you've taken George Lucas hostage. What would you do differently with the Star Wars Trilogies?
Here are some of my initial thoughts:
1. At least have Luke mention Uncle Owen and Aunt Beru once or twice after their deaths. With all the stuff blowing up and lightsaber fights, I can understand being distracted from it, like I was before a little scene in Robot Chicken, but it would be nice to see Luke bring it up at least once in the movies.
2. Dump the whole "Storm Troopers are clones of Boba Fett's 'father'" thing in Episode 2. (And get a better title by the way.) The Fett man was cool because of the Decemberween gift effect: He was cool because we didn't know the man under the mask. His mysterious past was whatever our imaginations could stretch it to be. Or even just assumed to be cooler than anything we really could imagine. Just have the storm troopers be clones of some nameless mercenary, or even just engineered from scratch.
3. Just for one of the elephants in the room: Get a better actor for Anakin. When the "romance" started, I was absolutely convinced Anakin was just playing her like a fiddle to create some kind of false "troubled but cute" image to pull Padme's heart strings. Turns out the actor wasn't acting like a bad actor.
4. Seriously trim down on the Ewoks.
5. For the prequel trilogy in general: Get George to make it very shortly after the original, and make sure he's still balanced by other directors, writers, editors and such. He was a cool guy, but getting protection from editors didn't help.