That time frame is ideal for salmon on both the Columbia River and the Oregon Coast.
Tillamook and Nehalem Bays will be heating up (Nearest towns are Tillamook, Garibaldi, Rockaway and Nehalem. The guys can fish while the girls shop, beach comb or explore. I would suggest Garibaldi House as a very nice place to stay. Boat rentals are available at the local marinas on the bays or you could do guided trips.
Fishing on the Columbia R takes place in several locations from Astoria to the Columbia Gorge. There are a few seasonal closure dates on some sections, but it will all be open for most of September.
If not familiar with the Columbia, a guide is highly suggested because of changing seasons as well as fast water, currents, commercial ship traffic and shallows. Please don’t hesitate to ask any more questions, I’d love to help.