Truth be told, I've stopped caring about the primaries. Whoever will win will win, and I will gladly support them in the general election. My California primary vote is still undecided. Whomever the nominee picks for VP won't matter than much, because our candidates all strong-minded (unlike Bush) and unlikely to die in office (unlike McCain, or Giuliani).
However, the composition of the cabinet will be quite important in determining the policy course of the next administration. For example, Bush's heavily neocon 1st-term cabinet (with the token Powell) told us more about his policies than any campaign promises, and Clinton's neoliberal pick for Treasury, Robert Rubin, closely coincided with the globalizing policies of that administration. (Admittedly, this is a chicken-and-egg question: do cabinet members influence policy that much, or are they picked based on their policies?) (To answer myself: Both.)
Therefore, I am calling on all the Democratic candidates to pick Paul Krugman for Secretary of the Treasury. As both an economic and political heavyweight with a broad base of support, a pre-election announcement of intention to nominate him for Treasury could further energize the Democratic base. Most importantly, in his New York Times column he has been very, very right about everything that has happened in the economy under Bush, and we need someone with his level of insight into the economy to help fix the mess that Bush made of it.
So once more, with feeling: Paul Krugman for Treasury!