Suggest cities where we should live? (Details inside.)

My partner and I want to move somewhere. Here is our criteria:
-liberal/socially progressive/gay friendly/artsy
-reasonable cost of living (decent homes available under 300k)
-jobs available in the art/design/advertising sector
-mild winters preferred, but not absolutely required
-lots of parks/green spaces and proximity to outdoor activities
-within an hour of a major airport

Size does not really matter, nor does geographic location for the most part. We are also open to international locations.

Ideas?