Close But No Cigar
Originally Lauren Holly auditioned for the part of Caitlin “Kate” Todd, but the producers felt that Holly would make a better fit as the director Jenny Shepard. All in all, a good choice.
Reasons, Reasons
Speaking of Kate. Sasha Alexander won that role instead and when she was killed off in season two, fans speculated that it was the producers decision to let her go. However it was Alexander who wanted out. Apparently she found the hours exhausting.