My two cents.
ASM 1
Introduce Peter at high-school. Don't need to show origins, show them in an opening title (like "The incredibile Hulk"). Introduce Mary Jane, Gwen, Harry, Flash Thompson and Liz. Introduce Curt Connors and Miles Warren as Peter's professors.
In the movie we'll see the death of Uncle Ben and Peter became Spider-Man after this event.
Show the origins of
Electro, an engineer who - after an accident - gave superpowers. In his first "mission", Spider-Man defeat Dillon and police imprisoned him. Dillon (isn't already Electro, only a common thief with powers) meet
Vulture - Adrian Toomes - in prison. He's an old thief, imprisoned for years. Thanks to some "mysterious" helps (i don't know, sure writers find a solution

) he has build a couple of wings that can permit him to escape. But he can't do it alone so he makes a deal with Dillon: Dillon will help Toomes to escape and help him to rob banks (because Toomes is old now) and Toomes will help Dillon to find and kill this new superhero who has send him to prison.
Meanwhile Peter falls in love with Gwen and some stories like these. Introducing in the movie also Aunt May, Anna Watson, Captain Stacy and Norman Osborn as a mysterious scientist father of Harry. Peter begin to work for Daily Bugle as a photographer: so introduce Jameson, Betty Brant and Robbie.
Take inspiration from
Marvel Knight's
Mark Millar's run when Electro e Vulture kick-Spidey-A**. I'd love to see this on his first adventure because the two villains are adults while Peter is only a teenager who tries to be a superhero. It will be "gritty" and "realistic" like studio wants.
Take inspiration, also, from the
Stan Lee's original comics and
Spider-Man: Blue by
Jeph Loeb.
In the end Vulture is imprisoned again but Electro must die because in the movie Vulture is only a thief while Electro is a criminal who wants kill the superhero. No MJ kidnapped or Gwen. Only Electro vs. Spidey.
In the very end we'll see Connors make esperiments on himself.
...................
ASM2
Peter continue to be a superhero and a normal teenager. He's fiancè with Gwen and other stuff.
Connors will became the
Lizard because from the end of the first one to the begins of the second one he continue to make experiment on himself.
Spider-Man won't kill Lizard but he's a menace for New York. Meanwhile Daily Bugle make a campaign against the new hero and New York is with the journal.
A cruel and psycopatic man, name
Kraven, go to New York to kill the Lizard. But Spider-Man try to stop him so Kraven going mad and think to kill both. Daily Bugle reclaim Kraven as an hero because he will kill two menaces in one.
Adapting
Kraven's Last Hunt changing Vermin with Lizard. Introducing also Connors' family: they give an emotional storyline to the whole movie.
In the end - after a cruel battle - Kraven decide to kill himself because he's the bad guy of this story and not Lizard or Spider-Man. Spider-Man helps Lizard to became again Connors and this is a sort of happy ending, again "gritty" and "realistic".
..............
ASM 3
Final chapter? Or not (if they cast young actors they can continue after third movie with others three films)?
So, Peter continue his double life and Captain Stacy knows his new identity.
I don't know if they must introduce two villains or only one but they must transform Norman as
Green Goblin. Yeah, i know that in the first Spider-man movie directed by Raimi there are Goblin but...Well, they can make different. First of all they have developed Norman for three movies and second they can make him different (like Nicholson's Joker and Ledger's Joker, for exemple).
One thing only: adapt the
Gwen's death storyline. In the end Gwen must die.
......................
This is my idea of a whole new trilogy. After a third movie they can explore the couple Mary Jane-Peter and introduce villains like
Sandman,
Shocker,
Doc Ock,
Mysterio,
Venom and why not
Black Cat (maybe in a fifth one when Peter and MJ stay together and this new female...Broke the...you know what I means).
What do u think?

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