I've driven through Astoria on the way to or back from, never stopped for more than a beer and lunch. It's more on the river than the ocean.
I don't know that you'd like it because tourists, but I go to Seaside often. There's a pretty basic hotel I like with a patio right on the beach, which is great for dogs and running and sitting and drinking. And there's a decent amount of dog-friendly places throughout the town. Kind of on the way out of town to the south is a little restaurant called Ruby's that loves dogs.
I haven't stayed there, but Cannon Beach is chiller/classier Seaside from what I've gathered.
I did a night in Yachats at Fireside Motel, another place that caters to dogs. It was mainly a break in driving between Seaside and the next stop near the CA border. It was pretty nice, more of ocean observing than beach. The hotel was a bit outside the main part of town so not great for pak'n.
Last Oregon stop was just north of Brookings within the Samuel H Boardman corridor. Stayed here a couple nights -
https://www.whalesheadresort.com/ - it's an old trailer park where owners have bonkers manufactured homes that qualify as trailers for tax purposes and rent them out through this resort. This is the specific one I stayed in:
http://whalesheadbeachresort.com/ but looks like they no longer allow dogs. There's a tunnel that runs from the resort under the highway and to the beach, but it's also super easy to drive or walk up and down the corridor to different areas.
All that said, if you're not on a set schedule and can be on 101, you'd be in fine shape winging it and stopping off at places that look interesting and staying if they're great.
