I live in the Grant Park/Irvington neighborhood on the east side and some years there are a lot of decorated houses and lots of kids. Last year there wasn't so much but enough to be interesting. There were many middle and high school students.
The most activity seems to be later; around 7 or 8.
We went trick or treating in my daughter's neighborhood last year. We were almost the the only ones on the street. I wonder if families aren't allowing children to trick or treat. There seem to be more group and community parties going on.
My brother lives in Tigard, on a street with large apartment complexes. He said he had no trick or treaters last year.
You could drive around the night before Halloween and scope out decorations which might help you know where to go for trick or treats.
We enjoyed the lack of groups and my 9 yo granddaughter didn't mind. She received more individual attention than she did in my crowed neighborhood the year before. Of course she was the cutest gypsy girl that ever was. lol