I'm actually not that fond of Peter Weller's voice or delivery, so I'm not thrilled by this news. As for Wade Williams, I'm not sure what to think. I really liked his voice when he appeared in "Civilization" on Enterprise
; I thought it had a rich, Orson Welles-like quality. But I found him underwhelming as Black Mask in Under the Red Hood
, though perhaps that was more to do with the character than the performer.
And it's interesting that Michael McKean plays the doctor who gets the Joker released, since McKean played the Joker himself in the Silver Age segment of The New Batman Adventures
' "Legends of the Dark Knight." He also played a Mutant gang member in that episode's other segment adapting a portion of The Dark Knight Returns
Ariel Winter has played Princess Perdita in both the character's screen appearances, the Green Arrow
short and a Young Justice
episode, but I don't remember what I thought of her performance. I'm unfamiliar with David Selby. (But IMDb says he's from West Virginia, so I'm puzzled by the suggestion that he'd be playing Alfred.)