I'm afraid that I'm old school James Bond, I'd take things back to the way they used to be.
Key to casting an actor for the role of Bond is they need to be relatively unknown previously. While we have great and fascinating potential in established actors such as Hugh Grant (wonderful funnyman), and Ewan McGregor who satisfy the need for ability, suaveness, Britishness and sense of humour, they are too well known for previous roles. So my shortlist consists of a mix from TV and stage actors, soldiers, explorers and adventurers. I would consider, Bear Grylls, Tom Ward, Goran Visnjic (yes the surprise entry), Rupert Penry-Jones, plus Hollywood regulars Eric Bana and Michael Fassbender. Perhaps because of Penry-Jones previous appearance in BBC series Spooks, I would be most inclined to cast him, he has the public school image, but with a bad boy twist.
The Girl, traditionally there are many featured in each film, with cameo appearances, and those of them who get killed off, not to mention Miss Moneypenny. Then there is the one who lives (often saved repeatedly by 007). For me the leading Bond Girl does not necessarily have to be an exceptional actress, but has to deliver an glamorous impact, Amber Heard would be ideal, The role of Moneypenny would have to go the the classically English, Emilia Fox.
The Ultimate Bond Villain, was the Megalomaniac Ernst Stavro Blofeldt, portrayed by Donald Pleasance in You Only Live Twice, nobody has epitomised that manic (and slightly comedic) evil as that. Actors such as Alan Rickman or Anthony Hopkins would be ideal, particularly when provided with an opportunity to overact to ridiculous levels. Mark Gatiss, Derek Jacobi, and Jean Reno could also be considered. My casting for archnemesis would have to go to Alan Rickman, purely on his peculiar speech mannerism.
So to sum up:
Rupert Penry-Jones as James Bond
Amber Heard as Lead Bond Girl
Alan Rickman as Arch Nemesis
Additionally:
Emilia Fox as Moneypenny
David Jason as Q
Edward Fox as M