If I may add to the conversation: I have shot entire weddings with the 56mm (non APD) for any shot of less than 3 individuals and all candids at a reception. I never felt the need to want "more bokeh" out of those shots. They were just right. I've also been able to shoot 250 shots of a senior portrait session wide-open at 1.2 without ever feeling like it wasn't close enough, etc.
In my opinion, if you are a portrait photographer, the 56mm feels perfect in terms of giving your subject enough space to be comfortable without being too distant from them. Not that 90mm would be too distant, but unless you have the space, 135mm equivalent length is pretty tight for portraits of anything other than headshots.
