I'm guessing you don't live in the Pacific Northwest, V. =)
You're on the right track, but you mangled the details. Both Washington and Oregon have some of the most liberal people in the country, but also some of the most conservative. In other words, we have some of the widest political spectra in the Union. There is also a high ratio of libertarians, who tend to be anti-government but will split on social issues.
In both states, the liberals outnumber the conservatives, and both states vote Democratic at both the state and federal level. This trend has evolved over the past twenty years as the Republican Party has completed dismantled its liberal wing.
As for the taxation thing: Oregon has no sales tax and Washington has no income tax. So if you live in Washington and shop in Oregon, you get a good deal. (And you get the worst deal if it's the other way around.) The number of southern Washingtonians who shop in Oregon isn't all that huge, however. It's not very convenient in terms of time, and for smaller purchases it isn't economical.
Oregon is mildly hotter than Washington, primarily because it is farther south. The University of Washington runs an excellent probabalistic forecast site where you can see this mild effect in action right now:
http://www.probcast.com/The much bigger climatological divide, however, is between the west halves of the states and the east halves. The western halves of Washington, Oregon, and northern California are a marine climate--mild and wet; the only such climate in the nation. The eastern halves of the same are arid and much more extreme in summertime highs and winter lows.
This climatological divide also correlates to the population distribution: in all cases, the western halves are more populous. They're also more liberal, both in urban areas (duh) and even in rural areas.
