Oktoberfest at Mt Angel is supposed to be pretty epic, but it's in September:
it's close to the main wine region of Oregon:
The Portland marathon is October 9th. Registration for the half marathon is already closed, but you could still follow some of the route. It's packed with live entertainment.
As Bider has mentioned before, McMenamins Edgefield is a fun place to stay if you want to check out the Columbia River Gorge. October is an especially lovely time to hike in the area and there is the Hops festival and harvest festival in the very charming town of Hood River.
Staying at McMenamins Kennedy School would put you close to the Alberta Arts district, which is full of cute indie boutiques, cafes and bars and gets a little crazy on Last Thursday, especially before Halloween.
Besides all of the great coffee, food and beer, there are also several distilleries clustered together:
Last year, the glass blowing studio where I take classes had a "blow your own pumpkin" dealie that is fun and doesn't require experience. I'm guessing they'll be doing it again this year.http://elementsglass.com/
The Benson is a great place to stay. http://www.jupiterhotel.com/
is also fun and puts you next door to a great place for live music.http://www.acehotel.com/portland
is another in a great location