Paul Giamatti as Tony Peterson(present) and Revrend Trask (1795)
I thought about Paul Giamatti as Willie Loomis. And if you wanted a scuzzy, ratty Willie Loomis, I can't imagine anyone better than Steve Buscemi.
I love Buscemi, but personally, I have had my fill of Willie "Jim Fyfe" style. Monaghan would do well by it, however.
I tend to see the the role of Willie as it developed on the original series: someone who initially comes under the thrall of the the vampire and is a very unwilling servant at first, but greq to not just depend on one another but also care for one another. Wille and Barn need to have a very close bond beyond just that of blood. I am not suggesting anything homoerotic, just a very subtle closeness just under the surface of the vampire/thrall master/servant distance.
As for other casting choices, I like the idea of Hathaway as Vicki but based on Devil wears Prada, she seems just this side of "hey, I'm so cute, aren't I?" Has anyone seen Becoming Jane yet? I hear she is good but I would like to see the Vicki character with more range.
I love the idea of Jason Issacs (Lucious, oops I mean Lucius Malfoy) as Roger, and leave the accent! I love Edmonds stilted stiff upper lip New England Old money pretension.
Having just seen The History Boys film, I would also love to see Griffiths as Stokes.
Not watching much current TV any more, The Lost references are, ahem, Lost on me
, but how about:
Zach Quinto (Heroes) - Peterson/Trask
Billy Piper (Rose on Doctor Who) - Carolyn or (perhaps better) Angelique
John Barrowman (Captain Jack on Doctor Who/Torchwood) - Joe Haskell
Allison Hannigan (Willow) - Vickie perhaps? Or Maggie?
Frances de la Tour (Madame Maxime/Mrs. Lintott (History Boys) - Julia or Mrs, Johnson/Abigail, or Elizabeth/Naomi
Helena Bonham Carter - possibly as natural for Angelique, but lets cast against type and make her Josette, in a potential 1795 Flashback Film.
Penelope Wilton (Harriet Jones, Prime Minister) - Elizabeth