I agree that she was very very graceful and lovely - I think she's amazing altogether - but Hitchcock famously said she was like a snowy volcano, that her cool elegance was a veil of what she could really be like (she had several affairs with her leading men, including quite a few that were married, and had a few affairs post-marriage as well... not that Prince Rainier wasn't doing the same).I think her most true biography is her cinematography, and her marraige, and her children. Her legacy is exemplary of what it is to be a lady at all times.
Not that I'm suggesting her elegance was fake or anything, I just don't think it was Grace's intention to have people make a saint out of her or anything like that. I adore her for her human-ness and how despite everything that was expected of her and how she was treated at times, she tried to do the right thing and make others happy. She was lovely.