Hi, you've posted this on a forum which is nowhere near the coast, but hopefully others will click on out of curiosity, as I did, lol!
So you have decided to go with rustic/camping?
Yurts? The truth about yurts is that given the sheer numbers of campers in the spring/summer/fall along the Oregon coast, the yurts are very few and far between. They book up many months in advance, however, you may still be okay booking now for late Sept.
Here is a good search site for SP yurts. You can check each section of the coast, then scroll down and click on "Camping" then also Alternative" (yurts etc).
http://www.oregonstateparks.org/searchpark.php
Most (but not all) communities with bays will have fishing charters; the most popular run out of Depoe Bay and Newport. Nearly all Oregon beaches are "good"! Some are much more easily accessible than others. Most of the "beach" state parks have easy access, but the campsites and yurts will not have ocean views with the exception of about half at Beachside SP near Waldport. The only KOA Kamping Kabins with a view is in Waldport, and that is on the bay, not beach.
Agates depend upon the winter tide and storms to wash out the sand. Here is some info:
http://www.romantic-oregon-coast.com/agates.html
I'll add to the list Lost Creek SP, day use, about 6 miles south of Newport.
North coast: Can't remember if I gave this to you before? This is in Cannon Beach, scroll down page for cabin info:
http://www.cannon-beach.net/searanch/sites.php
Beachside SP is a good central coast location. Cape Blanco on the south coast has cabins, I think one has an ocean view. It's a long walk to the beach though. Not sure if Bullards Beach near Bandon has yurts or cabins.