Doug Jones...I had to research that name. Do you mean the actor who played Abe Sapien in the "HellBoy" movies?Are you wanting Jones for his nearly emaciated physique? (that sounds wrong.) For a major motion picture, it wouldn't be that critical since a six limbed character like Arex would be most likely computer animated for the bulk of his sequences. If, on the other hand, you're wanting Jones for his cultured voice, yes, I admit I rather enjoy his calming tones. But to hire him to do a severely nasal inflection kinda' defeats the reason for getting him in the first place.
Who should voice M'Ress? I'll be honest with you; I never cared for Majel's performance. It just seemed so "forced". Besides, since she's passed away, we'd have no choice but to pursue other voice artists. But whom? That's a toughy. Hmm...if it weren't for the sad fact she too has died, I'd sya, oh, maybe Eartha Kitt. She had a trilling, almost purring like quality to her voice, but unlike Majel's, it was her actual conversational voice, so it sounded more "natural".
I'm sure several on these board would opt for someone else, so it'll be interesting whom they'll suggest.