Seems to me that if she wanted to pick a female senator around her age she'd be more likely to go with Amy Klobuchar.
Well Klobuchar supported Obama in 2008. She's not a Clinton insider, so not happening. Secondly, Klobuchar contrasts too much with Clinton in her folksy persona, which is not favorable to Clinton. Better to double down on the strong, experienced professional woman--and Shaheen, who has been both governor and senator of a key swing state and knows how to fight tough elections is arguably the second most qualified woman to be President in the entire United States.
How about Martha Coakley?
Hmmm... would make Hill look really good. Clinton/Coakley v. Walker/Brown LOL
Massachusetts would be tossup. LOL