I asked a friend who moved to Oregon about what she thought. Her 
comments below!
Cheers,
Linda

Hi Linda!
 
We LOVE it in Corvallis. It's been 8 years since we moved here, and 
we're very happy with our choice. I can't remember how much you know 
about Oregon, so forgive me if I'm repeating things you're familiar 
with.
 
The art community here is small, but rich and, as far as I can tell, 
friendly and supportive. I haven't been as active as I should be in 
some of the groups & events in town, but I am slowly getting my nerve 
up. Here are a couple of examples:
http://www.artcentric.org/
http://www.oregoncrafted.org/
http://www.corvallisfallfestival.com/
The proximity to Eugene and Portland (45 mins and 90mins, respectively) 
mean that we have access to larger galleries, events, markets, and 
suppliers.
 
The housing prices in Corvallis are still very reasonable (as compared 
to Seattle, certainly).
 
The weather here in the Willamette Valley is generally drier and warmer 
than the Seattle area. Last summer we had 90 days without a drop of 
rain in the summer...
 
Oregon State University adds some diversity to the town, though since 
it's the state's agricultural university, it's not a flamboyant 
diversity. There's also a strong engineering college, and HP has a big 
campus here, so high tech does influence the feel and economy of the 
town (in a good way, we think). 
 
For a much more artsy, edgie scene, Eugene is the place. The U of O is 
there, and the fine arts and social sciences colleges, so it's more 
overtly liberal and colorful than Corvallis. Ken Kesey bought land 
outside Eugene and started the Oregon Country Fair there 
(http://www.oregoncountryfair.org/), just to give you a sense of the 
'vibe' there. We prefer the more low-key feel of Corvallis, but some 
people like Eugene because it's more 'radical' and, of course, it's 
bigger.
 
I'm not sure Corvallis is a great place to move if you're single and 
looking for a partner. I've heard from men and women, young and old, 
that the dating scene is fairly non-existent. That said, I think if 
you're looking for community in general, and you become active in the 
arts or other activities that you enjoy, the town is small enough that 
you can connect with people fairly easily.
 
If your friend is looking for somewhere else that's relatively small in 
Oregon, Ashland is also great town. It has more of a California feel 
because of the proximity to the border, and it's a lot wealthier. The 
Oregon Shakespeare Festival is located there, so the arts community has 
more of a theater focus, but plenty of other types of art thrive there. 
Plus with the wealthy folks coming to see the plays, there's a thriving 
art market. Housing is quite expensive tho.  The weather is even warmer 
there than in the willamette valley.
 
Those are some thoughts off the top of my head. Let me know if your 
friend has more specific questions!