Tillamook Cheese Factory!! Take a tour, eat cheese curds and enjoy and ice cream cone in the sun - all within minutes of the beach. Trust us its SO fun. Also, highly recommend taking the scenic route from Carlton via Meadowlake Road to Trask River Road - it's beautiful.
Portland is one of our favorite cities - incredible food (check out Russian restaurant Kachka), vintage/thrift shopping, bars, parks, Portland Japanese Garden and more. Maybe don't rush to your lodging from PDX and explore the city a bit first?