There were a lot of bad moments in the Star Wars prequel trilogy, but few were as eyeroll-inducing as Padme's whiny pleas to Anakin about how he was breaking her heart and her subsequent death by lack of will to live in Revenge of the Sith. But it didn't have to be that way! Concept artist Iain McCraig, who worked on all three prequels, shared a different vision from Lucas' early drafts.
You can watch the whole video if you want, but skip to 30:19 for the relevant bits.
According to McCraig, in the original ending, Padme would have realized much sooner that Anakin was falling to the Dark Side. Knowing what this would mean and having seen Palpatine declare himself Emperor, she would have rallied support from Separatists and any who would join her cause in order to form the Rebel Alliance.
She also would've taken a bit more direct action against her former love. While in the final film, Padme flies to Mustafar and just kind of cries at Anakin, the original version had her pull a knife on the fallen Jedi. Apparently Anakin wouldn't have even resisted, though even with the blade to his throat, Padme couldn't bring herself to kill him.
From there, McCraig said, the film would've followed a similar trajectory to what we got. So presumably Padme still would've died from the worst medical diagnosis in the galaxy, but at least she would've gone out with a bit more glory. Oh well. At least we've got new Star Wars movies to look forward to.