Yesterday, I went to a discussion thingy with Gregory Maguire, Stephen Schwartz, and David Stone (one of the producers).
I've been trying to sum up the salient points, but it's a lot harder than when it was just Maguire.
Maguire seems to be quite a character. He said that he originally wanted to write a book, during the Gulf War, examining good and evil to make sure that he didn't "accidentally become a psychopathic killer." His first thought was Hitler but scrapped that after about 20 minutes because it would be too much work. And then he thought of the Wicked Witch, poof! the rest is history. He was actually quite funny. He also said that he really wasn't too concerned with how purist the musical was, since his book was just an off shoot of another book/movie, and so on. His major reservation with the show was the end. He said it took him a long time (over a year) to come to terms with it and really didn't think the show was going to work, but now really likes it.
Stephen Schwartz is the reason that Wicked is a musical. A friend mentioned it to him on a snorkeling trip and he called Mark Platt the next day, before even reading the book, asking for the rights. We almost ended up with Wicked the movie. It was already in the works, script being written, etc. Thankfully, Schwartz was able to convince Platt that Wicked needed to be on stage. The script was reworked extensively. It started way back in 1996(?) and took seven or eight years to put together.
David Stone talked more about the process of putting the show together as a Broadway musical. Kristin was always Galinda, and the role was written for her. Stephanie Block read for Elphaba in workshops, but the role was not written for her. Someone (Mark Platt?) wanted to do an ART production first to get the fee for it, but Joe Mantello wanted to mount a full production because an ART couldn't do the full sets and tech. They started out in San Fransisco and did a run there. After that, they closed the show down entirely for 3 months (which cost them $2 million) to rework it. The most significant cut IIRC was the funeral of Dr. Dillamond. And the rest is history.
That's all I can remember for now.
(I've had Defying Gravity on repeat for the last half hour or so.