Alice Ripley, Billy Porter, and Lee Wilkof in LITTLE SHOP OF HORRORS
Paula Abdul, Marisa Tomei, and (I think?) Jenna Elfman were announced for revivals of SWEET CHARITY at one point or another. Jane Krakowski did a reading too, but I'm not sure if she was ever announced for a full production.
Mary-Louise Parker was announced for a revival of DESIRE UNDER THE ELMS to be directed by David Leveaux. It was cancelled when she went to Broadway with PROOF instead.
Joe Morton was originally announced as Lord Capulet for the recent Broadway revival of ROMEO AND JULIET, but withdrew for SCANDAL.
Laura Benanti in THE VIOLET HOUR (replaced by Dagmara Dominiczyk).
"You travel alone because other people are only there to remind you how much that hook hurts that we all bit down on. Wait for that one day we can bite free and get back out there in space where we belong, sail back over water, over skies, into space, the hook finally out of our mouths and we wander back out there in space spawning to other planets never to return hurrah to earth and we'll look back and can't even see these lives here anymore. Only the taste of blood to remind us we ever existed. The earth is small. We're gone. We're dead. We're safe."
-John Guare, Landscape of the Body