I grew up in Oregon City, a few miles South of Portland. Lived there for 22 years, traveled a bit, now live in Vegas (14 years). Go back 'home' often.
As everyone has said the Portland area in the Summer (July - Sept) is awesome. Perfect weather and everything is green and lush. Then it turns and by March it gets real depressing. Parts of Portland I love, but not sure I could do the 7 months of overcast/drizzle again after living so long in sun. And visiting for a weekend or week during this time isn't going to cut it. A week of drizzle can be refreshing. 7 months in is another story.
If you're interested in farming but being close to the city/action a place like Oregon City or Beavercreek might be for you. 20-30 minutes from downtown but tons of rural space and a small town feel. Then if you can, plan on traveling Jan - April.
