The best raspberries for pots are the "ever-bearing" type rather than the traditional raspberry plants that just bear fruit in July and also the more compact bush raspberry varieties.  The newest  variety that has made a great impression in Western Washington (and also in my garden) is called "Raspberry Shortcake" as it is also self pollinating and does not need staking. It gets two to three feet tall. One more contender is called "Heritage" and this raspberry variety grows to five or six feet tall with berries that freeze well.  Your climate in Western Washington is ideal for growing raspberries so good luck and Keep Growing, Marianne Binetti