There are two more women I think would be serously considered. For Obama, having Kansas Governor Kathleen Sebelius as a running mate could accomplish pretty much everything you say McCaskill would but could also help in neutralizing criticism of Obama's lack of executive experience. Being a governor also inherently makes her a Washington outsider which would maintain the whole "change" aspect. She could also put a red state into play and maybe even some of the surrounding states. For McCain, Governor Sarah Palin of Alaska is generally considered a rising star in the Republican Party. She seems to be regarded as a strong conservative, particularly on social issues, which could help him with Huckabee supporters. She is also, obviously, a woman, quite young and a Washington outsider, helping McCain to counter some of the criticism he will face as an old white man who has been in Washington for 25 years.