As an interesting aside to the previous post, there are only two states where those making at least six figures voted more heavily for Obama than those earning five figures or less did. They are the SWPL states of Oregon and Colorado. Portland, of course, is often noted for its distinction as the US' most SWPL city. And I've been to Estes Park.
Taking the Democratic-Republican margin among high income earners and comparing it to the same margin among low income earners is probably a fairly decent way of assessing state-level SWPLness, actually. I'm sure there are more direct measures that would be superior to that approach, however.