Always great to see other people who can see past Portland. I grew up there and I only visit now. It's different to say the least.
I've got a friend in the Aloha/Hillsboro market that's doing both flips and buy and holds. He's been able to house hack a flip and rent to old coworkers.
I'm personally a big fan of the Salem market myself. The broadway area is up and coming. The kids at Willamette U are looking for places nearby to live that are kind of trendy and safe. That downtown section is going to be really catching on soon. Pay attention to it and if the numbers make sense make it happen.
Areas to avoid is tough because Salem has pockets all over. Even in South Salem there's a trailer park surrounded by bad apartments 2 blocks from a really nice golf course with hoa's and constant development.
What growing up in Portland taught me about real estate is some places end up really rebounding through concentrated efforts to revitalize an area. I would never set foot on Alberta as a kid. Now I take my kids there.
I guess my point is use your better judgment and keep gathering more info.
Corvallis and Eugene are worth looking at too. Honestly within 2 hours of Portland you'll find what you want in any direction. Southern Oregon like grants pass Medford and Ashland have a ton of activity and lots of buyers from California Nevada and Colorado.