Who would you cast as Sam Cooke? Taye Diggs, Anthony Mackie or...?

Don't know much about history, but I do know that Sam Cooke (1931--1964), the legendary soul singer-songwriter of "You Send Me," "A Change is Gonna Come" and "Wonderful World," is the subject of a planned biopic penned by the authors of The Commitments and Across the Universe. 

Who would you cast to play the King of Soul, possessed of the soul-stirring voice (he began as a gospel artist) and velvet delivery? Do you go with Taye Diggs, who starred (and sang) in Rent? With Anthony Mackie, who has the stronger acting chops (and has proved himself a deft comedian as co-host opposite Hoda Kotb this week on the Today show)? With a singer/showman like Usher?

Sam Cooke, cooking at the mic.

Cooke, shot to death in disputed circumstances by the manager of a Hollywood motel when he was only 33, was a meteor and entrepreneur: 29 top-40 hits in seven years -- with his own record label and publishing company.  He sang of love ("Bring it on Home to Me," about social concerns ("Chain Gang") and even in death was the soundtrack to the Civil Rights movement ("A Change is Gonna Come).

Looking forward to the film, although how do you make a movie about someone who didn't have a third act?

Casting suggestions? Favorite Cooke song? Best use of a Cooke song in a movie? (For me, the answer to the last question is a tie between "Change is Gonna Come" in Malcolm X and "Wonderful World" in Witness.)