Monk has always been hit and miss for me.
While I've found her to be excellent in scene stealing comedic roles (much like Carmen in "Curtains,") there seems to be something missing when she is required to portray characters with a wider range of depth (her Joanne in "Company" is a prime example.)
Though she'd undeniably be an interesting Mama Rose, I'm not so sure she would be as excellent as you may think.
Tonya Pinkins: Then we had a "Lot's Wife" last June that was my personal favorite. I'm still trying to get them to let me sing it at some performance where we get to sing an excerpt that's gone.
Tony Kushner: You can sing it at my funeral.