@Greg Moran
A lot of people have difficulty adapting to our rainy (west side) weather. I would say that if they are limiting their areas to the west side of the mountains then now would be a good time. Much of the west side of WA/OR stay pretty grey from about November to March. The further south, the less grey. If they will be going east of the mountains late spring would be better since the roads can be unpredictable this time of year, especially if they aren't used to driving in snow.
Summer will allow them to experience a lot of the outdoor activities available since the weather will be drier and more things will be going on outside. If it is more of the inside stuff like museums and theater then any time is good although be aware that at least WA is still pretty limited in what is open. I think OR is a little less restrictive.
Since I'm not sure what kinds of activities they are interested in or how much it is hard to recommend what could best suit them. Eugene has a University of OR so would have many of the typical college town things. On a smaller scale, McMinnville has a private college (Linfield). McMinnville is also about 40 minutes to Salem and about an hour to Portland. Vancouver is closer to Portland and all of those activities. It sounds like they also have friends there so that may be a good place for them to start or end in. Also, heading out toward Hood River would get them close to a lot of outdoor activities.
Heading further north, being reasonably close to Seattle would give you lots of activities but it is hard to get close enough to Seattle and still be rural. Out on the eastside the price tags are pretty high but there is still some nice rural properties. North of Seattle the prices are a little more affordable. Western Washington University is located in Bellingham which might be a place they would like. There is reasonable, rural land outside of the city. Bellingham has a lot of people who are environmentally oriented. It is on the ocean and very close to the Canadian border. It is going to be cooler than Portland area.
There are also a lot of beach communities that might fit what they would like. Maybe start in southern OR and meander their way at least to Vancouver area if not all the way north to Bellingham. Don't forget the San Juan islands and Olympic Peninsula. My family has had property in the Peninsula for most of my life. Much of it is rural. Sequim has grown quite large and has been popular with retirees for years. It is called the banana belt since it supposedly gets more sun. (The Hoh rain forest takes much of the water. BTW, Hoh rain forest is the only rain forest located in the lower 48 of the US.) Port Townsend and Port Angeles also offer some activities they might like.
If they want to check out the east side I would have to say that Bend may offer what they would like. It is a tourist town with both skiing/winter sports and summer hiking/water sports. Also, Spokane is a pretty substantial city with a lot of rural areas surrounding it.
I'm sure they will find something they like, it is just a matter of getting out and seeing it. If nothing else, they would have a pretty cool vacation.