I would go for Kate Winslet for Magrat. I get the impression that Magrat is supposed to be in her thirties. As for the pale, washed out look, they can use make up. Look at Charlize Theron in Monster or Cameron Diaz in Being John Malkovich.
I think Maggie Smith would be the best for Granny. What about Tina Malone for Nanny Ogg?
Any suggestions for Agnes Nitt?
