Interesting, guess I'll do a partial list of my own:
Harry Dresden - Chris Evans 
http://www.imdb.com/name/nm0262635/ Specifically check 
Push for his action and grungy abilities, and the Fantastic Four films for wit and wryness as the 
Human Torch.
Thomas Raith - Brad Pitt.  The first Dresden Files book I read was 
Small Favor, and I immediately pictured him in that role.
~Papa Raith - Vincent Cassel.  See 
Ocean's Twelve for the raw menace he can portray, and just as quickly change it to suave affability.
~Lara Raith - 
Ebenezar McCoy - Rip Torn.  The man's name and look bring to mind images of an aging wolverine, which I think suits Eb perfectly.
~Ancient Mai - 
~Arthur Langtry - Sir Ian McKellan.  I would've said Sirs Ian Holm or Christopher Lee, but the first is kind of on the small side and Lee is too outright-menacing 

~Joseph Listens-to-Wind - 
~Martha Liberty - 
~Rashid - Alexander Siddig.  He played the man Orlando Bloom spared in 
Kingdom of Heaven, who turned out to be Saladin's Chancellor.  A very witty, but grave, guy.
~Aleron LaFortier - 
~Gregori Cristos - Bill Nighy.  He'll be playing Rufus Scrimgeour in the last Harry Potter film, which I see as kind of similar in appearance to this role.
Michael Carpenter - Jeremy Irons.  Seen the 
Kingdom of Heaven?
~Molly Carpenter - Dakota Fanning.  Again, see 
Push.
~Charity Carpenter - Sandra Bullock.  Yep.
Mab - 
~Maeve - Megan Fox.  I hate hate hate her, which I think would be great fuel for this role.
~Lloyd Slate - Viggo Mortenson.  I think it would be a 
great role for him, definitely breaking the mould from how he usually performs.
~Leahansidhe - 
Uriel - Morgan Freeman.  He's done God before, yeah, but I can't get him out of my head for playing Uriel (all shape-shifting aside!).
Mac - Bruce Willis.  Done.
Wooh!  I'll fill in the blanks later.