Buzz--
I love Dame Judi as Elizabeth, even though she is in her 70s, which is why I suggested Kate Hudson as Carolyn, because she's could believably play a 25-30 year old woman. I don't know her actual age, however. For me, I like to think of Elizabeth as the shuttered, lord-of-the-manner, aristocratic type, that isn't overly welcoming, but isn't completely insensitive and rude either. She's got secrets to keep, a family to protect, so from an outsiders POV, she's going to give a little shiver while being motherly at the same time. So I think Dame Judi or Helen Mirren would probably be able to convey this.
Angelique needs to stay a blonde, and I have to give a resounding NO to the idea of Angelique Jolie. She could play seductive, but we need someone who can be seductive, challenging, vindictive, bitchy, and smarmy all at once. After seeing Cate Blanchett in "Notes on a Scandal", I'd simply die to get her and Dame Judi in the same scene together again!
As for Julia, I think Moore or Janney could pull it off. Either one could be calculating, productive, lustful, and piercing all rolled up into one.
I'm afraid that I want and hope that the producers/casting directors shy heavily away from the younger Hollywood crowd--Hayden Panetierre, Lindsay Lohan, etc--because I just don't think any of them have the credentials or acting ability that would blow me away.