The Pacific Northwest, also known as The Great Northwest is known for it's pioneering spirit. Note how you go "Out West" or "Back East". As a group, those living out here prefer to have much less growth than we get. Now that we're here, we wish everyone else would stay home. There are lots of cute bumper stickers to that effect.
Like most generalities, they break down when folks interact 1 to 1. Anyone who comes "Out" to visit will have a great time. The folks aren't as friendly as "down south", but that isn't to say they are unfriendly. They will just respect your space more.
If you come out and use Seattle as a "Home Base", here are several "day trips" one might consider.
Mt. Rainier is 1-2 hours away, depending on where you enter the park.
Look up the San Juan Islands and see what all the Puget Sound has to offer.
A variety of day cruises that include trips to see Orca Whales are available here.
Over night trips that take to to visit Vancouver Canada, Victoria Canada, and Bellingrath Gardens. Train service is also available to Canada (2 hours away) or you can boat up and train back.
Portland Oregon is 2.5 hours south. You can take the train there and enjoy all of downtown without a car. The Saturday Market worth a day alone. The microbrews and NE Portland nightlife can keep you busy. If you drive to Portland, Mt Hood is an hour away and you'll want to visit Timberline Lodge where they filmed The Shining. They have ski and snowboard camps all summer at Mt. Hood.
Half way between Seattle and Portland is Mt. St. Helens. There is plenty to do there and you can turn the 2.5 hour trip into a full day if you divert to the North Rim where the view is breathtaking. Drive all the way to the Johnson Creek Observatory if the road is open, meaning the volcano is resting. The various caves around there are really worth your time. There are ones formed by gas flumes and others when lava encased huge trees and they rotted away leaving an "inverse" forest you can crawl through.
In Seattle one must visit Pike Place Market, The Space Needle for the view, or a 45 minute drive will get you to snow at Snoqualmi pass. The kids went skiing there at least 30 times this year including last week (mid April). Over 200" of snow fell this year and fun was had by all.
Lots of great history about Seattle on the Underground Tour. Additional info here and here.
Some great glass art comes from Seattle. Mimish gave me a 4 week class for Christmas in '05 at Art by Fire. The instructor was great and I loved the class. There is a wonderful free exhibit down town in the Seattle City Centre Building. It is on Pike between 4th and 5th Streets.
We're getting more wineries a short drive away, and there have always been lots of microbreweries as eastern WA produces much of the worlds hops.
Seattle is home to one of two functional Cinerama theaters in the world. The second is in England. We watch all significant movie premiers here.
In addition to preserving the Cinerama, Paul Allen built the EMP and we have the worlds larges Science Fiction Museum. Thanks Paul!
Don't forget to visit the Weird Science Solon in your spare time.