We've got a stand of mature sugar maples on our property up here in central British Columbia, and I've just finished boiling down my first gallon of syrup from them. Someone was kind enough to bring them out here around 50 odd years ago, and it sounds like no one out here had ever gotten around to actually tapping them. You can grow sugar maples out here in the PNW, but for a good sap run, you need nights below freezing, and days above freezing. We had around a 5 week season this year and I got around 160 litres of sap from six trees.
Good luck! Also, black, silver, douglas, and big leaf are all worth tapping and boiling if you can find large enough tree (10" diameter at chest height is the minimum size). Also, make sure you collect the sap at least every other day. It's like milk and will go sour on you if you leave it too long. I found it easier to just toss some plastic carboys full of sap in the freezer until I had enough to be worth boiling down.
