PDX
check with Priceline for cars, we usually get them fr $16 -$20 / day, but Multnomah County (PDX) (and Clackamas County have VERY HIGH rental taxes) I expect it is still your best bet, but a painful expense.
I prefer the 'west 26 rte. UNLESS it is a very clear day, then go up I-5 to Castle Rock, WA Exit and drop by the St Helens visitor center (Very near I-5).
Then back to Longview and out to Astoria. (We have stayed at "the Cannery", spendy but nice.
We have Halibut and Chips + Chowder at The Sea Breeze (at the intersection of 26 and hwy1), slightly north (1/4 mile) towards Seaside
Be sure to spend time at Ecola and Hug Point State parks. (near Cannon Beach)
Walk north (towards, Cannon Beach) from Hug Point and see the caves, water fall, and early 'stage-coach' road with good tide pools.
Manzanita is a bit more laid back (Non-tourist) than Cannon Beach
Twin Rocks has great drift wood beaches
Surfside Resort - Rockaway Beach, OR has inexpensive rooms off season / midweek
Tillamook Cheese Factory for a sample of Cheese Curd. Nice quilt and pioneer museums in Tillamook.
Take '3 capes' go see Octopus Tree and mini light house
We have stayed here sandlakecountryinn
Oregon Coast Bed and Breakfast, Oregon Coast Lodging pretty nice and quaint (quiet / weekday) we were the only guests.
Depot Bay is nice for being close to a ROUGH ocean
Otter Crest is a nice place to stay. (listen to crashing waves at night)
Welcome to Newport's Yaquina Lighthouses - Friends of Yaquina Lighthouses nice spot
Hatfield Science center is worth a visit
I like the tide pools in Yachats, be sure to spend time down in the area right off the 'in-town' parking, as there is usually nice tide pool stuff (winter could be less so)
the beaches and coast at Brookings (I'm personally not a fan of the dunes area, but they are a huge attraction for many)
We usually camp, so I don't have much info on lodging.
Most folks like Moe's Chowder. It's fine and they have other affordable options.
Do a search on this forum, as there are many good hints for day trips / coast
I'm partial to The Columbia Gorge, and the Beach, but there is lots to see. You might not need lodging, just keep traveling! (and hope for a full moon)