An umbrella would be smart, but a jacket with a hood will work perfectly well. Sweaters year-round, decent sneakers, sandals for summertime (last part of July/first of August). Here, dressy typically means GAP-wear and casual says "I Was Cleaning My Garage Today;" we're pretty low-key people. If a place wants you to wear a tie, they'll say so up front.
Toiletries and Medical Supplies: Whatever you use to keep your hair looking just so, pack it in your tote bag because you may be caught in a bit of rain - which means either a wet head or crushed hair from a hood. But don't discount sunscreen because the sun does shine, even through the sprinkles. And lip balm is always good.
Photo Equipment: We have lots of lovely things you'll want to remember seeing (and you can get great shots of you with Mt. St. Helens, Mt. Hood, and the Columbia River in the background), so bring that camera. Just about every drugstore here will download & print digital pictures for you.
Camping/Beach/Outdoor Gear: Tons of places to camp & hike, and you can play all along the banks of the Columbia River. However, it is usually chilly in the woods (and always frigid in the river) so gloves & hat are a good idea.
Luggage and bags:
This is up to you, however in the northwest we like to pack light, minimal load full of maximum function.
Clothing/Shoes/Weather Gear: WINTER, FALL: Rain gear, Umbrella, pants, sweaters (not to burly), stick with tennis shoes or other protective foot gear, in sandals you'll be wet and cold.
SPRING: Yuu can lighten the heaviness of the clothes but be prepared for rain. Umbrella.
SUMMER:Sun and more sun, shorts, tanks, sunglasses and sandals.
Toiletries and Medical Supplies: Dont forget your toothbrush. If its summer better bring sunscreen.
Photo Equipment: Allow for no sun in the rainy season fall - spring.
Camping/Beach/Outdoor Gear: I would avoid camping anytime but Summer or youll be cold and wet most of the time. Atleast check to forecast and make sure the clear skies will hold up.
Miscellaneous: Always check the forecast our weather is sun one minute rain the next!