Some interesting suggestioins
Johnny Vegas - very interesting, a good serious actor when it's needed and it would a different approach
Eddie Izzard - again serious when required and a different approach
It's a shame I can't see a way for Donna (Catherine Tate) to be worked in as the new Doctor - it's nothing to do with "it's time for a woman" but because she could rip the whole thing up - one minute head butting Cybermen, the next compassion to melt the heart of a Dalek. In many ways stronger than any of the Doctors so far.
Milton Jones - hmm... potential there but I haven't seem do any dramatic acting and would like to be surprised.
As for the Cummerbatch etc. suggestions - same old, same old.
Helen Mirren - see her in RED and you won't have any doubts.
Let's dare do something!