There has been some marina growth in the past few years, that should help you.
When I moved up here, it took a long time to figure out where was where. It's pretty complex geography, and that can make things confusing.
Look at 48° North - The Sailing Magazine
, our local sailing magazine, for information on slips and available boats.
Shilshole Marina, outside Seattle has just remodeled and I am pretty sure there are available slips. They are pretty cagey about this. You should call them directly to get the straight scoop.
Elliott Bay Marina just outside Seattle has slips available. There's an empty one right by artbyjody!
There are slips available in Poulsbo, a nice town. A bit of a trip to get to open water from there.
The marina at Bremerton has just been rebuilt/expanded. Should be availability there.
Another marina remodel at Bellingham, too
These new slips also relieve the pressure on the other marinas.
How's that for a start. If you require more information, just PM me, and I will try to help you out.