I was just signing off when I saw Bree's comment about Cary Grant. And thinking - if Cary Grant had played Bogart's role, then Audrey Hepburn wouldn't have had a crush on William Holden in the first place and then the whole movie would have had to be rewritten. If Bacall had played Sabrina, Bogart would have been too distracted to play the efficient businessman. He would have had to play Holden's role and the ending would have had to be changed.
Interesting bit of trivia, Bree.