The laws are the same for tourists, as for residents. Anyone 21 years or older, in Washington State, may purchase and hold up to 1 ounce of useable marijuana, up to 16 ounces of marijuana infused product, like brownies, and up to 72 ounces of liquid marijuana product. Paraphernalia is also legal. You can partake on private property, away from the view of the general public. Do remember, that some hotels are non-smoking and if they don’t allow tobacco smoke, they won’t allow marijuana smoke, either.