Former Labor Secretary Robert Reich would make a superb candidate for VP because on the campaign trail, he could demolish the flawed economic plans of the Republican with especial conviction and vigor and knowledge.
He interviews very well on TV, is articulate and convincing, and in my view, likeable. I think he would absolutely destroy the Republican economic arguments, concisely and accurately.
Additionally, he has executive experience, as Labor Secretary. And, at top universities, a highly successful career as an economics professor, a very intellectually demanding discipline.
Additionally, and very very important, he is a declared progressive (see his writings).