Diane -- I'd go with Michelle Pfeiffer. I'm totally biased.
Will -- James McAvoy.
Rafe -- Honestly, he's the hardest. It's not that there aren't actors who can do it, more a matter of finding the one who seems perfect. I'm going with Harry Treadaway.
Tess -- Tilda Swinton. (Or perhaps Deborah Ann Woll.)
Kaab -- Rosario Dawson.
Vincent -- Peter Facinelli. (I could also see Chris Hemsworth.)
Micah -- Tough cast. A young Bae Doona or Amber Benson could probably do it.
Madeleine -- Could we have Ellen Kushner do a special cameo for her?
Saabim -- LaTanya Richardson Jackson
Joshua -- This is where I'd put Tom Hiddleston. (Or possibly de Bertel.)
Chuleb -- Chadwick Boseman. He's supposed to be almost too young and beautiful. (Unless, of course, you want to keep Boseman for Ahtul / Arthur in season 2.)