Well, ahem, haha, I wish I was well-connected and in-tune, however I think I mostly just got lucky in starting up a thread that got people talking. That and my penchant for obsessively saving whatever I think could be useful information.
The one thing I can say, and I don't know if this'll answer your question, is that Portland and Seattle seem to have a way of standing out as "The Powerhouses" in "the world of poly cities." As mentioned
earlier here, Seattle has been called (by whom?) "the poly capital of the world." At the same time, I've heard tons of rave reviews about Portland's poly scene, and so far no bets on which of the two cities would "win that contest."
But if you have the freedom to be sufficiently picky about what city you move to, and you really want to be in the center of a hotbed of poly activity, then I would suggest try Portland or Seattle, whichever of the two you think you'd like best.
Now, that's based on bits and snatches of info and I'm sure argument could be made for this or that other city being an equal contender with Portland and Seattle. (Some might say Victoria for example?) I'm just giving expression to the overall vibe I've gotten so far.
I want to add that I'm repeatedly thinking about adding Columbus (Ohio) and Santa Fe (New Mexico) to the list. I kind of want to hear some kind of testimonial from someone else before I do though; I can't decide if I've heard enough yet about those two cities to add them to the list.
But yeah, I'm pretty darn sure Portland and Seattle are particularly heavyweight poly powerhouses.