I've lived my whole life in Oregon, in the southwest suburbs of Portland, although I'm very new to UX, so I'll tell you what I can.
The Kinton schoolhouse is great to take pictures of from the outside, but stopped being structurally sound a decade ago. It's also next to the local grange, which is quite active, so it's best to steer clear.
The Deer Creek house is a promising spot, although I haven't had the chance to visit it myself.
Pros- Empty since 2002, with possible homeless habitation between then and now (the police cracked down pretty hard a couple of years back, no one lives there anymore, at least to my knowledge), interesting construction, a second story was added later by raising the existing story and building underneath it. Lots of graffiti, some of it quite good I presume, a the only local graffiti artist lives just down the street, I don't suspect by coincidence.
Cons- Next to a semi-major road, so you have to keep your lights down. Also, lots of broken glass.
The big spot you should visit though is the Highway 30 house, just before you get to Sauvie Island if you're going north. I'll attach a picture so you can see why people like it so much. Apparently, the groundskeeper lives in a trailer in the driveway and has let people in who wanted to take photos before. I heard that a few years back so things may have changed though.
Good hunting and welcome to Oregon!