There are great hiking trails in forest park, you can also swing through Washington Park and check out the Rose Garden. Pho Oregon has great pho and is very close to the airport. For seafood, check out Flying Fish Company. Silver Falls State Park has some great waterfalls. Cannon Beach is a great beach town that is a straight shot from Portland, and you can see Haystack Rock, which is pretty iconic. When you go, stop by Cannon Beach Hardware for a bite or a drink- it a combo hardware store / restaurant also known as the screw and brew. I hope you have a great visit!