I never thought about Zach Quinto but he is possibly locked up with the Star Trek franchise for the foreseeable future unless he would have time to film stuff in between the wait. I just like Patrick Dempsey so much. It was really seeing him play a charming but kind of punk ass type character in "Transformers: Dark of the Moon" that convinced me he would be perfect for the part.
I think a "Doctor Strange" film would have so much potential. I already have a visual sense of the magic and dark arts practiced in the movie. I tend to agree that Dormmamuu would probably be depicted in CGI. I'd work my damnest to make sure it was realistic as possible.