If you’re going to go to Tillamook, you may as well drive up the entire coast and go to Astoria. There’s a fantastic maritime museum there as well as the delicious Buoy Beer. From the restaurant you can watch ships come in and try to cross the Columbia bar. The Columbia bar is the point where the Columbia River meets the ocean. Buoy Beer also has a glass floor in the lobby where you can view sea lions playing under the restaurant. The restaurant is situated on top of dock pilings.
There’s a trolly that can be ridden up and down the river/ocean front that is really fun (and cheap!)
Seaside Promanade can be fun. There are numerous shops and restaurants situated right next to the beach.
Cannon Beach is great, there’s a Mo’s there too. At this beach, you can see the iconic Haystack Rock.
In Newport, aside from the Oregon Coast Aquarium, there is the Hatfield Marine Science Center that is free. Nearby, down in Old Town, you can watch sea lions play.
Outside of Yachats, there is Cape Perpetua which has some of the best tide pools.
There is much to do at the Oregon Coast. As a native Oregonian, I think I’ve been to the entire coastline.