Playing pool is always a good winter past time.

Hunker down and look out the window. Seattle in the winter is that wet sort of cold. But on the plus side they got some of the best donuts and baked goods around. So at least you wont be disappointed in what you're eating while you're stuck inside.

things to do
 

Snowboard! snowshoe, winter camping, sleding, 4 wheeling, snowmobiling...

have lunch on the ferry and take some playing cards to pass the time.

There's talk about the Museum of Flight, but Boeing also has a tour of their 747 and 777 lines in Everett that is pretty amazing. That place is so huge is hurt my head just looking at it. Future of Flight - Aviation Center & Boeing Tour

Brew beer, so when the sun comes out you have beer to take along

I like to snowboard, go Jeepin and work on the Jeep in the winter.

The Seattle aquarium is always a good visit. Been out of the area for a while but when I grew up the family would plan on a day into Seattle, we lived out in the Kent/Renton area, and depending on the weather we would either go to the Woodland park zoo, aquarium or Science center. The woodland park zoo is even getting some good indoor exhibits so that you don't have to spend the whole time outside.

Because it seems unlikely anyone else will mention it, I'm tapping my bigleaf maple trees and freezing the sap for steam-boiling later this winter. You can tap maples, alders, birches, and I've heard tell about tapping willows and cottonwood, too. The bigleaf sap is a little lower in saccharides than sugar maples, but it makes dandy, delicious syrup. :)

Go to the Bellevue Botanical Gardens. They do a really nice light display. It runs for only the holiday season though.