My guess woud be that President Obama would select either Sen. Chuck Schumer or Sen. Dianne Feinstein. Both could get Congressional approval with relative ease. Both are experienced Both are from safely Democratic states. Neither one has Presidential ambitions.
Interesting answers.
Schumer would be up for reelection in 2016 when his term as VP would expire. If he became VP he would have to give up his Senate seat, another would be appointed to fill the seat, so I doubt he would accept the Vice Presidency if it meant he would not be going back to the Senate. Of course, he could always run for the Democratic Senate nomination for 2016 against the appointed Senator. It is also possible, of course, that the appointed Senator would want to serve only for the balance of the Senate term to which he was appointed, which would allow Schumer to run for the Senate in 2016 unopposed for the Democratic nomination.
Feinstein is 81 years old, so I doubt Obama would pick her.
Please understand I make these points not to criticize these choices, but simply for discussion purposes.
But your picks are most interesting.