I don't know Oregon especially well, but have good memories of past visits to Corvalis (OSU). Eugene (UofO, ugh) is perhaps my absolute last choice in the entire region, but some people like it. I hear mixed things about Salem but don't have enough experience to say more than that.
In Washington, I'll second Tacoma. I love that town and would like very much to live there myself; however, should be aware that while its neighborhoods are great, the downtown area has only recently begun to recover from decades of abandonment. It's got some nice features and mountains of potential (plus potentially great views of the mountain) but if you need hustle and bustle downtown, look elsewhere. Transit connections to Seattle are pretty good, by very poor regional standards at least. In-city bus service has suffered due to lack of support from the rest of Pierce County in levy votes. The city is looking to expand its short light rail line to the Hilltop, which is affordable and interesting but perhaps not yet ready for the truly skittish. Colleges include: the University of Washington-Tacoma, Tacoma Community College, Pierce College, Pacific Lutheran University, the University of Puget Sound, and Bates Technical College.
If that's a little too big for your tastes, Puyallup is actually pretty nice and affordable. It's a little more conservative and rural feeling than Tacoma. It has heavy rail commuter (only) service and bus links to Tacoma and Seattle. Be aware that snobby north King County residents look down on all of Pierce County as well as south King Co. That's their loss, though, not yours.
Olympia's been pretty well described already. It has the advantage of probably having some of the best public schools of the affordable semi-urban west side of the mountains. It has the Evergreen State College (alternative) and South Sound Community College.
Everybody loves Bellingham, but if your kids love it they will have a hard time finding jobs to allow them to stay on as adults.
I like Spokane but have only visited a few times. I'll let others speak to its merits and shortcomings. I should visit again soon. Gonzaga University is there, as it Spokane Community College.
Walla Walla is a dot of semi-liberal surroundings and fancy wining and dining in the heart of eastern WA. Not sure about prices there these days though. You've got both Whitman College and Walla Walla CC there.
If I had only one suggestion to make, though, it would be this: avoid Seattle, with gusto. It's become far more expensive than it used to be, is seeing heavy development, traffic is bad, transit is okay, schools are iffy, and while I-90 provides an easy shot to the mountains, most of the trails that are close in are choked with hikers on nice weekends. FI would improve trail conditions for you as you could go on weekdays, but I've been hiking the region for nearly as long as I've been alive and it's crazy how busy the mountains are.