You're probably just as likely to get shut down by an afternoon thunderstorm in the Rockies than rain in Squamish. That said, go to the Rockies - the mountains are bigger!! and you won't have to worry about ever running into Dru.
Parking might be an issue on Sundays though.
Seriously, though, the eastern portion of west seattle would be a good location for you b/c its a pretty easy bike commute over the bridge to sodo.