I live in NE Portland but many years ago I lived in Hillsboro. The entire way between Portland and Forest Grove could be considered one town. Yes, there are city boundaries but the main highway going thru all those towns has constant businesses and homes. There are still more rural areas outside the cities.
What is probably more important to choosing a town in which to reside is finding a home that is an easy commute to his work. Traffic is terrible in many parts of that area. Is he going to work in a major or mainstream company? If so his company will be able to provide all sorts of helpful information.
I also suggest that you look at different city's web sites. The ones surrounding Hillsboro are Beaverton, Aloha, Cornelius, Forest Grove, Banks. A highway map will also give you a clue as to commuting routes.
Also check out the Chamber of Commerce sites.
When I lived in Hillsboro it was definitely a town. It looks like a city to me now and I wouldn't recognize the boundary.
I lived in Tempe for several years and moved back to Portland ten years ago. If I can help you look for houses let me know. I suggest, that if at all possible you come look at the area if you've not seen it before. I'm no longer familiar with specific towns and their amenities but I can still navigate the area. If you have questions about the location of anything specific I may be able to help.
You will not have difficulty finding nearly everything you want from where ever you live. The area is compact and full of activities and services. When I lived in Hillsboro, close to downtown, I drove into Portland frequently. It was about a 30 minute drive. Now we have MAX, a light rail system and you can get to nearly anywhere quickly using public transportation.