For Queenie, I'll be interested in how Olivia Colman plays it –she is cast somewhat against type. Having said that, Claire Foy does a wonderful job of showing the 'relatable, "real"' individual behind and beyond the persona and role she has been somewhat moulded into, so there is a 'nice' side to the character, I think.
I think Tobias Menzies has that slight arrogance/unlikeability that's good for Prince Philip, but I'm not sure he's physically imposing enough. Maybe David T – also has an unlikeability, but is (or at least seems) a bit taller and more looming.
I really want Paul Bettany to do it, but that doesn't mean much because I'd happily watch him hanging out his laundry.
Margaret... hmm. I love Anna Maxwell Martin but, not to be horrid, I'm not sure she's beautiful/sexy enough to be Margaret. I think the current actor is wonderfully cast in terms of looks and manner, as well as her performance being brilliant.