Peter Parker is supposed to be a nerd and one day he gets bit by a spider and gains powers. I think the Perfect Peter Parker/Spider-man would be Aaron Johnson (Kick-Ass). Johnson played a great role in Kick-Ass, the characters are similar so I think he can play a great Spider-man.
Mary Jane Watson is Peter's love interest and next door neighbor. Mary Jane should be played by Emma Stone(Superbad and Zombieland). Emma Stone has the right look and is a good actress.
Aunt May is Peter's sole care-taker. Aunt May should be played by Helen Mirren (The Queen). Mirren is an oscar-winning actress and has the right look of Aunt May.
Uncle Ben is Aunt May's husband. Uncle Ben dies and this inspires Peter to become a super hero. Uncle Ben should be played by CLiff Robertson (Spider-man). He is the Uncle Ben in Sam Raimi's Spider-man. He was one of the few choices I liked.
J. Jonah Jameson is the editor-in-chief of the Daily Bugle. For this role, i Like Tom Selleck(Magnum P.I.). Selleck is a golden globe and emmy winning actor.
Felicia Hardy aka Black Cat. Is an ally of Spider-man. Amber Heard(Never Back Down) would be a good choice for Felicia. Could you imagine Amber in the Black Cat costume, that sounds like a dream come true.
Gwen Stacey is another love interest of Peter's. Gwen should be played by Sara Paxton(Superhero movie). Sara has the right look and is a good enough actress to play her.
Guidelines to making a perfect fan fiction article.
Harry Osborn is Peter's best friend and son of Spider-man's arch enemy, the Green Goblin. Harry should be played by Evan Peters(Kick-Ass and Never Back Down). Evan and Aaron have chemistry together as best friends because they played best friends in Kick-Ass already.
Villians: (im not saying they should all be in the film im just saying they would be good in the roles)
Norman Osborn aka the Green Goblin is the Spider-Man's "Joker". He is the arch enemy of Spidey. Jeff Goldblum(Jurassic Park) would be a great pick to play Norman. As seen in Jurassic park, Goldblum plays a good part as a scientist.
Eddie Brock aka Venom is also a photographer for the Daily Bugle. Eddie is jealous that Peter gets all of the pictures of Spider-man. Eddie brock should be played by Kellan Lutz(Twilight series). I know what everyone is saying no way someone from twilight will be in these movies. But, this guy can actually act and he looks the part of Eddie.
Cletus Kasady aka Carnage is the spawn of Venom. I think that Cillian Murphy(Batman Begins) would play a great Carnage. The role would be like when Scarecrow goes crazy at the end of Batman Begins.