Many other people have done this before and I will take my turn at it. I'm not 100% for a Spider-Man reboot since I feel there was too much left that the Raimi movies could do, but beggars can't be choosers and I'll put up my ideal casting for the Spider-man reboot. I did as many as I could think of.
Shia Labeouf as Peter Parker/Spider-Man
Thinking of an actor for Spider-Man is really hard but of all the popular young actors in Hollywood currently Shia Labeouf is the best. I can't see anybody like Robert Pattinson, Taylor Lautner, or Zac Efron in the role. Shia has proven himself to be a very capable actor, is used to acting in big franchises, and can be the cool and geeky character Peter Parker needs to be.
Anton Yelchin as Harry Osborn
A rather recent rising star nowadays. He has proven himself in STAR TREK and TERMINATOR SALVATION. I think he'd be a great choice for Harry Osborn. Of course in a sequel he'd have to become a villain.
Kristen Stewart as Mary Jane Watson
I know what you're thinking, no I'm not a fan of TWILIGHT, I don't care for it. I do like Kristen Stewart though, particularly her performance in THE MESSENGERS. I personally think she is a good actress and could make a pretty good Mary Jane.
Scout Taylor-Compton as Gwen Stacy
You could say I'm a fan of Scout Taylor-Compton. I love her as Laurie Strode in the recent HALLOWEEN MOVIES and can't wait to see where her career heads. She is nice looking but can pull off the more bookwormy look which they could give Gwen based on how she is in the TV show THE SPECTACULAR SPIDER-MAN.
Glenn Close as May Parker
It will be hard to follow up Rosemary Harris but Glenn Close has proven herself to be a really good actress, and I think could do the role well as well as differently then done in the last series.
Jon Voight as Ben Parker
Another one that will be hard to follow up is Cliff Robertson but Jon Voight is a very good actor and could pull the role off well.
Hugh Laurie as J. Jonah Jameson
Speaking of actors that are hard to follow up J.K. Simmons was the epitome of J. Jonah Jameson, and may be the hardest to re-cast. If anyone can do it, it is Hugh Laurie. He's very good at acting a jerk but at the same time being very entertaining while doing so, his acting in HOUSE is the perfect example of that.
Danny Glover as Joseph "Robbie" Robertson
A good veteran actor that could pull off the honest and stalwart newspaper worker of Joseph Robertson. I liked the guy in the original series but they should give the character a bigger role this time around.
Danielle Harris as Betty Brant
She looks the role and is a pretty good actress.
Harrison Ford as Captain George Stacy
Harrison is a great actor and one do a great job as the tough cop, and the loving father roles that George Stacy has.
Kristen Bell as Felicia Hardy/Black Cat
A good and gorgeous actress who has been doing way too many romantic comedies recently. She'd do a good job in the role of Black Cat.
Jason Isaacs as Norman Osborn/Green Goblin
My first thought was Daniel Day-Lewis but then I realized he'd probably never do it, but then I though of Jason Isaacs. Jason Isaacs is great at playing villains such as his character in THE PATRIOT and Lucius Malfoy in the HARRY POTTER series. He could play both the cold businessman and maniacal villain very well. Since he was the villain of the first film in the original series and to let his character develop he shouldn't be the main villain in the first one. But he should be in it, perhaps as a background villain but not Green Goblin. That is something that should be in a sequel, and perhaps they could have him kill Gwen in this series like he did in the comics.
Philip Seymour Hoffman as Otto Octavius/Doctor Octopus
Everybody knows how great of an actor Philip Seymour Hoffman is and if you've seen MISSION IMPOSSIBLE: III you know that he can pull off being a great villain. Another villain I wouldn't imagine as the villain in the first but he should appear to be set up to be the villain for a sequel. Perhaps like in SPECTACULAR SPIDER-MAN he could be a scientist working for Norman Osborn.
Sam Worthington as Eddie Brock/Venom
My original thought was David Boreanaz but I'm going to go with Sam Worthington. He's another rising star and has the proper physique and acting chops for the role. Obviously Venom couldn't be in the first movie but Venom like Dr. Octopus should be set up for. I think this time Peter should have the symbiote in one movie it goes onto Brock at the end, and Venom would be in the movie afterwards rather than compressing his whole story into one movie.
Jackie Earle Haley as Cletus Kasady/Carnage
What can I say about Jackie Earle Haley that hasn't already been said. He is a great Academy Award Nominated actor. Looking at him as Rorschach, his role in Shutter Island, and now he's playing the role of Freddy Krueger I think he's make a fantastic Carnage since he can play insane and villain quite well. He'd probably be in the movie with Venom and be the threat that forces Spider-Man and Venom to work together to stop him.
Adam Baldwin as Flint Marko/Sandman
He's great at playing tough guys and does look the role.
Kevin Durand as Alex O'hirn/Rhino
He has the physique for the role and there's just something about him that makes him perfect for Rhino.
Christian Slater as Herman Schultz/Shocker
I find him to be a pretty underrated actor. I can't explain it, but there's just something about him that makes me think he's be a good Shocker.
Ben Kingsley as Adrian Toomes/Vulture
Ben Kingsley is a great actor. Most people know it. He was in talks for the role for SPIDER-MAN 3, but obviously that didn't happen. John Malkovich was reportedly going to take the role, and he could do a great job as well, but right now I'm going with Ben Kingsley.
Oded Fehr as Sergei Kravenoff/Kraven the Hunter
Do I have to say much? I mean look at him. He looks perfect for the role. Plus he's a pretty good actor.
Paul Bettany as Dmitri Smerdyakov/Chameleon
This is another great actor who just feels right for the role. Since they're half brothers maybe he and Kraven would Appear together in one of the movies.
Timothy Olyphant as Mac Gargan/Scorpion
For some reason casting Scorpion is extremely hard but I'll go with Timothy Olyphant. He's a good actor, and has played great villains in the past.
Robert Knepper as Roderick Kingsley/Hobgoblin
I'll be honest I didn't know he even existed until he appeared as Samuel Sullivan on HEROES, but seeing him in that role immediately won him over for me as an actor. He could play the evil and maniacal Hobgoblin with flying colors.
Anthony Stewart Head as Miles Warren/Jackal
An underrated actor who if you seem him act knows that he could play the teacher Miles Warren, but also the villain the Jackal. A perfect example of this would be his role in REPO! THE GENETIC OPERA. He'd obviously be the main villain if they decided to do an adaptation of the Clone War storyline.
Robert Englund as Phineas Mason/Tinkerer
Yes I'm choosing Freddy Krueger himself for the Tinkerer. If you've seen him in the web series FEAR CLINIC, which if you haven't you should watch, he's good at playing dark intellectual villains. Plus he genuinely looks the role.
Benicio del Toro as Michael Morbius
A good actor and he looks the part.
Dwayne Johnson as Lonny Thompson Lincoln/Tombstone
I know what you're thinking, all Dwayne Johnson really does nowadays are family films. I have no clue why he chose that career path, actually yes I do they make money, but he has done more mature films before. I think he has the physique for it and all around would make a great Tombstone.
Malcolm McDowell as Silvio Manfredi/Silvermane
A great veteran actor who is great at playing bad guys, and played a crime boss of sorts as Linderman in the TV show HEROES. He'd make an interesting rival to another crime lord who you'll see on this list very soon.
Dominic West as Hammerhead
Seeing as he died in PUNISHER: WAR ZONE and that the movie sadly probably won't get a sequel I could see Dominic West playing Hammerhead since I thought he did such a great job as Jigsaw. He could be a lieutenant to the next character I'm going to cast.
Ray Winstone as Wilson Fisk/Kingpin
Ray Winstone is a great actor and could pull of both the philanthropist facade and the coldhearted criminal sides of the Kingpin. He should start out as a behind the scenes villain possibly with a cameo at the end of one of the movies but eventually become a more main antagonist. Yeah Sony doesn't own the rights to the character but I can dream can't I.