Many have pondered various ways that they'd have done their least favorite films differently. "Spider-Man 3" is probably one of the most common of those films which people think of in such a way. I decided to share my idea for how it should have been done. I'm not making a full script or anything. I'm just giving the main plot points and such. Here it is.
The film would start out where the second one left Harry. He would be preparing to administer the performance enhancers to himself. After this: the screen would fade to black and we'd hear Harry cackling in a way that resembles the cackle of his father. Next it would show the scene of Peter M.J. where they are on the web. This scene wasn't out of place in the film and I don't feel that it would need to be taken out, except for the symbiote. I also wouldn't take out Peter telling Aunt May that he's going to propose to Mary Jane. The same goes for M.J.'s play and the parade. Though I wouldn't have Gwen in the film.
Anyway: the scene of Harry attacking Peter would be taken out and changed to a later scene where Harry is following John Jameson out of the theater and then cutting off into an alley. A moment would pass where John is standing in front of the alley, hailing a cab. Before a cab stops: a web hits John's back and drags him into the alley. The scene goes to the next morning where John, who is covered in webbing, is in a body bag that is being zipped up. Jonah is watching in fury/dismay as his son is taken away. He then pulls out his cell phone, goes through his contacts, and calls someone. We hear him saying something like "Gargan? I need your services."
We then cut to Peter and Mac Gargan in Jameson's office. Jameson is telling Peter that Gargan needs his help. They're trying to find Spider-Man and bring him in for the murder of John. Peter says that he doesn't know where to find him and that he's sure that Spider-Man would have left the city in order to stay away from being taken in for false-accusations. It would be at that moment that Spider-Man breaks in through the window and tackles Jameson. He'd tell him that if he doesn't want his wife to end up like John, he'll stop publishing papers that mark him as a public enemy. He webs him and then leaves. Gargan cuts Jameson loose from the webs and Jameson stands and calls his wife to tell her that he's making arrangements for her to go to a secret safehouse.
Then we cut to Peter in his apartment with M.J., crying. He's holding his mask and shaking his head, as the phone rings. A familiar cackle comes through the phone and then hangs up. Peter stands up and M.J. asks him what's wrong. He says that he knows who's framing him.
We cut to Harry's mansion living room, where he's sipping scotch and talking to his hallucination of his father. The butler walks into the room and says "Sir? Mr. Beck is here. Should I send him in?" Harry says "Go ahead" and then Quintin Beck walks into the room. Harry thanks him for all that he's done for him. He mentions that he's ensured that Spider-Man will be hated by the whole city. He then informs him that he'll no longer be needing his services, as he walks up to him. Harry then stabs Beck in the stomach with a letter opener and carries him out of the room.
Then we show Mac Gargan and Jameson in an Oscorp laboratory. They're talking to a scientist about an updated version of Osborne's performance enhancers.. The scientist explains that the only changes in Gargan would be enhanced strength, speed, and agility. He further explains that he will be wearing a suit that has a tail that will be controlled by his mind, using an enhanced version of the inhibitor chip that the late Dr. Otto Octavius created. The tail would have extreme strength and also the capability of launching a special kind of acid that is made by the tail absorbing enormous amounts of the bacteria in the air and fusing it with some of the air's moisture. Gargan agrees to the process.
The next scene shows Peter storming into Harry's mansion and demanding answers for what's happened. Harry pretends that he doesn't know what he's talking about and informs him that he doesn't appreciate the fact that Peter broke his mahogany door on the way in. The phone then rings and Harry answers. The scientist from the prior scene is on the line and is informing Harry that there were some slight complications with the Scorpion suit and performance enhancers. He further explains that the entire laboratory was destroyed and that Mac Gargan has experienced pure rage as soon as he came out of the chamber. Harry hangs up and laughs. Peter asks what happened and Harry shrugs it off as if it was nothing important. He then asks Peter to leave. Peter refuses to leave and Harry sighs while cracking his knuckles. He then opens a drawer on the table beside his chair and picks up a remote. He clicks a button on the remote and part of the floor opens up. An enhanced glider rises up and launches two bladed pumpkin bombs at Peter, as Harry escapes to his secret room for a moment and comes back out in upgraded Goblin armor. He looks a lot like his dad, but with some minor alterations. I don't know what the differences would be, but it would still look a lot like Norman's, anyway. The two fight for a little while and end up destroying Harry's living room. Mary Jane walks in through the door and sees this. Peter asks what she's doing there and she informs him that Aunt May said that he'd be there. He tells her to leave, but she throws a statue at Harry instead and insults him. Harry laughs and throws Peter aside, taking the time to greet Mary Jane. She's shocked that Harry is doing this. She begins to talk to Harry just as Peter tells her to move out of the way. M.J. jumps to the side and Peter throws a pumpkin bomb that he got off of the glider toward Harry. The bomb misses him and ends up too close to M.J. and kills her. Harry, now furious, clicks a button on his wrist and causes the glider to blast Peter with flames. Peter jumps out of the way and off of the balcony before much damage can be done. Harry kneels down at M.J.'s corpse and holds her tightly, letting out a few tears. We then hear Norman say "Harry! Don't let this weaken you. Now he has been taken down another notch. Now is the time to destroy what's left of his heart." Harry nods, presses a button that causes the glider to come to him, and jumps on it. The scene ends with Harry flying out his window.
We cut to Peter web-slinging through the city. While he's slinging, some acid disintegrates a web and he begins to fall. He shoots another web and catches himself. He then goes up a building and sees Scorpion. Peter looks at him for a moment and says "Mac? Is that you?" Scorpion snarls and says "How can you be web-slinging when I saw Spider-Man tackles Jameson while you were standing next to me?" he takes a moment to think and then says "You're a smart one. You really are. You hired an impersonator to cover your tracks. Well: you're not foolin' me!" He then blasts acid at Peter. Peter dodges and shoots web at Scorpion, who breaks the web with his hand. They fight for a few moments until Scorpion accidentally runs off of the building and smashes a car. We see him jump back onto a building and claw his way up, but Peter is already gone when he comes back.
Now we see Peter arrive at Aunt May's apartment. He knocks on her door and gets no answer. He continues to knock and then hears a familiar cackle. Peter busts down the door and sees Harry standing over a dead Aunt May. "You didn't think that I'd let you take M.J. and my father away from me without doing something in return, did you?" Harry says. "Bye, bye, little bug." Harry jumps on his glider, presses a button and flies off. Before Peter can follow Harry out of the building, there's an explosion that sends Peter flying out the window. He shoots some web to stop him from hitting the ground very hard. We see Harry hovering above the building. He shouts "Don't you know how to die?!" before rushing toward Peter and shooting a missile from the front of the glider at him. Peter dodges it but his grazed by a bullet from the machine gun that's attached to the glider. We then see Scorpion blasting the glider with acid, causing Harry to jump to the ground. "The bug is mine!" Scorpion says. Harry shakes his head and pats Scorpion on the back. "Be my guest, big guy." he says, just before backing away. We then see that Harry planted a bomb on Scorpion's back. The bomb explodes and causes Scorpion to fall to the ground, with his suit smoking. Harry walks back to Scorpion, picks him up, and throws him out of the way. "Now, where were we?" Harry asks. Peter says "If we're going to this: we do it right. Hero versus villain." He then removes his clothes to reveal his Spider-Man suit, and he puts on his mask. The two continue to fight until Peter points both hands at Harry and says "I never thought that I'd have to let loose, but here goes nothing." He webs Harry with much more web that Harry can't move. Peter limps away and the scene ends with a glimpse of Gargan's finger twitching a little.
The final scene is Peter walking away from the double funeral of his aunt and Mary Jane. We see Dr. Connors put his hand on Peter's shoulder. He says "Peter, if you want to get away from the city for a while, feel free to join me on my trip to Louisiana. You look like you could use a vacation." Peter politely declines and walks off by himself.
The end.
I know that it's nothing spectacular, but I think that it's a lot better than the film we were given. I doubt that they'd have let anything like this go through, though. It's quite morbid and has very little action where Peter is suited up.