When our kids lived in portland that was a must stop. Here is a idea that I have used. get bulk mailing boxes from the post office and preprint the labels. Pack you purchases and drop them off at the post office. If you are staying at a Hotel give to the front desk and they will take it to the post office for you. Love the place to shop but I always get into trouble.
Also if you get a box and haven't used up your luggage allowed on the airline pack a big box full and check it in That works also.
a Fun place to go . kjym Kathy