I've been wanting Rupert Grint for a while. He's ginger!
I've thought about that myself often, I'd definitely be interested in seeing him get an audition or even one of the Phelps Twins that played Ron's brothers Fred and George
I've seen Idris Elba floated many times, I don't see it, what intrigues people so much about him that makes them think he'd be good as the Doctor?
He wouldn't be. I've admired the guy for years, ever since he was the best thing about Ultraviolet (which is saying something) but he's not the Doctor. He's completely wrong for the part, and its not cos he isn't a good actor (cos he is) and it isn't about ethnicity (hey I'm the guy who'd still have Patterson Joseph).