1. Bryan Singer's X-Men 3
2. Return of the Jedi - lose the Ewoks, instead make it that the Empire are using slave labour Wookies on Endor, the rebels free them and they join the fight.
3. Attack of the Clones - Make it a bounty hunter extravaganza, they almost did this, but in the middle section have bounty hunters going after Padme and Anakin on Naboo, their romance blossoming under battle conditions.
Also, make it that Jango Fett organises a Mandalorian army with a deal he makes with the cloners, using the same type of clones intended for the Jedi, and that is what the Jedi fight at the end of the movie, as well as the droids. The Jedi wipe out the Mandalorians, and Boba is left as the last of them. Then have the Clone army come in as the droids and last of the Mandalorians are overwhelming the Jedi just as in the movie.
Improve the lightsabre fight between Obi-Wan, Anakin and Dooku.
4. Spider-man 3 - keep it much the same, but tidy it up a lot, lose the ret-con to Uncle Ben's death, make Sandman put Aunt May in a coma(during one of his sandstorm rampages) causing BlackSuit-Spidey to want to kill him.
5. Batman and Robin - Keep Kilmer as Batman, cast a great actor in the role of MrFreeze, lose all the crappy puns, lose Thurman's annoying Mae West voice. Get Lee and Janet Scott Hatcher(who wrote the original story and screenplay to BF) to write it, as long as it was at least as good as BF.
6. FFROTSS - Keep it much the same, but improve the action, and attach a third act where Galactus arrives on Earth, in person.
7. Iron-Man 2 - Don't have Whiplash locked away in a tool-shed for most of the movie, give him the souped up armour early on in the film and have him going on a rampage in the city, let's see Iron-man in more crime fighting scenes in the movie. The movie should also open with seeing him sorting out some war situations, instead of that kind of thing just being referred to in the headlines.