Not sure about the locals (I"ve found them fine and friendly). But a usual the letsrun crowd is overtly hostile.
Been to Bellingham on several occasions, 4-5 days at a time. seems like a good place with some pluses and minuses like anywhere. Great trails to run on. Mountains within an hour, and the coast is right there. If you want culture, Seattle is 90 minutes away, Vancouver an hour or a little more. Weather is generally good, but they get some big storms (wind and rain) in the winter that make outside running dicey.