Believe me, I am completely against a Star Wars reboot/remake, but I'm just considering my choices for the characters if it were to happen. Here are my choices for all of the Star Wars films main characters.
Young Obi Wan Kenobi-Simon Baker
He's terrific in the Mentalist, and is the ideal choice to replace Ewan. I can picture him as Obi clearly in my head, and he would also be great opposite my Anakin choice.
Young Anakin Skywalker-Andrew Garfield
He's a phenomenal actor, and in case you have your doubts see The Imaginurium Of Doctor Parnassus and The Social Network. He proved that he can play a character that seeks revenge and has a hatred for his original master.
Han Solo-Jon Hamm
He has played a sort of playboy before (See Mad Men) and he hsa proven he can play an action role too (See The Town). I would really love to see him in the part.
Luke Skywalker-Michael Cera
He's a great actor who knows how to play the innocent hero. He was fantastic as Scott Pilgrim, and can bring that hero type portrayal to Luke.
Or Alex Pettyfer
In case a more serious and adventurous Luke is needed, Pettyfer is the man for the job. He's a rising star, and a good one at that.
Princess Leia-Ellen Page
I really like the idea of Mary Elizabeth Winstead as Leia, but it's just to over used. So I decided on Page. She's a great actress, and has worked opposite one of my Luke choices in Juno.
Older Obi Wan Kenobi-Michael Gambon
His character of Dumbledore in Harry Potter is very similar to Obi. He is a teacher who trains children still learning of their world and powers, just like how Obi teaches Luke.
Lando Calrissian-Terence Howard
He was great in Iron Man as Rhodey, and playing the best friend of a cocky character will be nothing new to Howard.
Boba Fett-Jeremy Renner
He did great opposite Hamm in The Town, so he would be perfect as the assassin hired to kill Hamm's Han Solo. He has proven he can play a real aggressive criminal, so I think he can pull it of.
Queen Padme Amidala-Olivia Wilde
She did an excellent job as Quorra in Tron Legacy, and is familiar with Sci-Fi films. She would be a great love interest for Garfield in the later films.
Qui-Gon Jinn-Jim Caviezel
I honestly couldn't think of anyone for the role. I finally decided on Caviezel. I really liked his portrayal of Jesus in Passion of the Christ, and I think he can bring that same talent to the role of Qui-Gon. It would be hard to replace the brilliant Liam Neeson though.
Yoda-Toby Jones
He did the voice of Dobby in the Harry Potter films and Dobby is very similar to Yoda. If he can play Dobby, he can play Yoda, end of story.
C-3PO-Michael Sheen
He has that sort of robotic British voice to him, and can bring some of his witty humor to the role. So why not?
Darth Vader-Peter Cullen
He's done the voice of Optimus Prime from Transformers for years, and he can use that same powerful robotic voice for Vader. He would just have to make his voice a bit deeper.
Emperor Palpatine-Terence Stamp
If you've seen Superman 2 you know that Stamp can play an evil galactic ruler. After seeing him as Zod, I'm sold that he would make for a perfect Palpatine.