@ehBeth,
I don't think she would, either, plus Massachusetts is a Democrat lock, and it has been for a few decades now (I think the last time we went Republican was in the 1984? Reagan landslide. Before that, I think the last time we went Republican may have been for Ike). I also think Warren does better in the Senate, and Hillary could use a powerful friend in there.
I would look for someone in the South, Midwest, or West, preferably someone who brings in a decent delegate prize. E. g. Cory Booker brings a nice chunk of delegates, but I think he'd skew things too heavily East Coast. Plus I think he would do better rising up through the ranks. He's got a dynamite future if he wants it.
Two odd ideas from the Senate: Gary Peters - Michigan, up for reelection in 2020. 57 years old, was in the House before. Michigan currently leans Democratic and brings with it 16 electoral votes. It's a nice prize to have.
Other is Bill Nelson - Florida - up for reelection in 2018. 73 years old is potentially a problem, but the guy was a freakin' astronaut. Florida is a battleground state with 29 electoral votes. I doubt either side can win without Florida.
According to CNN, the current map gives Hillary 236 delegates to Trump's 191, with 111 in play.
Either candidate needs 270 to win. If Hillary gets Florida, Nevada, and New Hampshire, then the whole shooting match is decided, assuming all the solid predictions hold true.