My favorite thing to do in Portland is a street art tour. There are a couple websites that offer routes.
Forest for the Trees has bike routes. They have murals all around Portland, and every year they do new ones. It’s local and international artists. The ones this year are phenomenal. It’s self-guided, but they have them all mapped out. You could spend an entire day doing it. You could do a brewery and mural tour, or a coffee and mural tour. That would be really fun!
P’s and Q’s is also really cute. You can rent a picnic basket that they’ll pack with their sandwiches, and you can take it out on a picnic.