James McAvoy as Bilbo Baggins?

[Lalaith]

Whatever Bilbo's age, in the Hobbit he is an odd combination of a confirmed bachelor and a childlike figure - carried around on piggy-back by the dwarves when he gets tired and so on - so he should have an air of vulnerability. I think in that case they could do a lot worse than McAvoy.
I can't remember the bloke from Six Feet Under, I'll have a look.

But I really couldn't be having with Wood as Frodo. He was way *too* child-like and vulnerable, even for a Shire halfling, and besides which, LotR Frodo was not really much like Bilbo in the Hobbit.