I don't know about Daniel Craig as Lex Luthor but he played great villains in Road To Perdition and Infamous. Did good American accents in both too.
Daniel Craig strikes me more as Metallo (the STAS version anyway). Not sure about who works as Lex. Shannon is very good in Boardwalk Empire, I l liked Hamm in The Town, I think Billy Zane could pull it off, there's a lot of good options out there, which is a good thing.
I hope they go with the corrupt businessman angle because there's so many things you can do with that. It would give Lex resources, it wouldn't preclude him also being a mad scientist or some of the other things on the list. I do hope they include Mercy in the movie. It really sucks that SR was disappointing because Spacey was great casting, though I wish Peta Wilson had been Mercy.