As lawyers, we can't advise our clients on the best way to break the law. We also aren't supposed to break the law ourselves. It's that ethics stuff that you slept through in law school.
In Washington (and Colorado), it is perfectly legal to toke up. Recreational use of marijuana, thanks to state initiatives, does not violate state law. It does, however, violate federal law to buy, sell, smoke, snort, chew, or to do pretty much anything with weed. So, when a Seattle lawyer wants to partake in a state-legal substance, or advise a client on the best way to structure her pot dispensary corporation, he may just be violating the Rules of Professional Conduct.