Mount Ranier National Park.
There are neat little towns around Wenatchee.
Grand Coulee Dam
The beaches around Westport, Wa are really wild in the winter. Although further south towards Ilwaco is a bit nicer.
A short ferry ride to Bainbridge Island and back is quite nice, especially at night.
Vancouver Island in BC is a very nice place as is Vancouver, BC.
A
word of caution. If you are driving in the mountains, even if the weather seems nice stay on the main roads, and have plenty of emergency supplies. Things can turn bad quickly, don't get lost like that poor editor from CNET last winter in Oregon and not be prepared for it.
Even in the summer, it is a good idea to be prepared when venturing in the mountains.