Maria Friedman as Miranda??? How?
OK, I'm completely against the idea of the movie being turned into a stage musical (haven't read the novel though), it is one of those movies that rely a lot in the fact that it is a movie to succeed, IMO. I think it would lose all its charm and excitement on stage. Plus, Miranda--the film's Miranda--is a character than would NEVER sing. Sondheim has made shows about characters who wouldn't sing (he mentions the main reason COMPANY was structured so uniquely in terms of its score is because he felt none of this characters would sing in the typical book musical way). I can't think of any other composer who could make this work, perhaps Jeanine Tesori or Adam Guettel (if he would ever be interested in adapting this kind of material).
Having said that, LuPone is ALL wrong for the part. Miranda is a classy, quiet, understated character, none of those characteristics fit LuPone. Mind you, I have nothing against her, but you just need to look at the list of characters LuPone has played successfully and you'll know she would be miscast as Miranda (Evita Peron, Mrs.Lovett, Momma Rose, Reno, Cora Hoover, etc). Same with Debra Monk whom I adore but just like I can't buy her as Joanne, I could never buy her as Miranda.
Donna Murphy, Bebe Neuwirth (who played a similar role in HOW TO LOSE A GUY IN 10 DAYS), Julie White, and Christine Ebersole are much more appropriate for the role. Even Marin Mazzie would probably be a good Miranda in a few years.
I'd pick Anika Noni Rose, Erin Davie, or Lea Michele as Andrea and Jenny Powers as Emily.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"