I've always heard that Betty White was originally thought of for Blanche while Rue McClanahan for Rose based on their past roles. However, I've heard both wanted something different so they switched parts.

I wish they had shot an episode with Betty playing Blanche and Rue playing Rose. I think it'd be cool to see what might have been.

I guess basically it would have been like Betty playing Sue Ann Nivens and Ellen Harper and Rue back as Vivian on Maude and Aunt Fran on Mama's Family.