I have been living aboard, in the Tacoma WA area for the last 8 years. Its a great way of life, and the best cruising area in the world (just a little biased).
As to my recommendations on boats, really need some idea of your price range. Most of my time has been spent on a Catalina 34. Great boat for the local area, but I think it might be a little light for coastal work. I have known people to take them places I wouldn't go (around Vancouver Island) so this kind of depends on your experience. Its a great live aboard boat for 1-2 people. Sails well, good construction, if not up to the standards of a Morris or a Swan. A 34 or 36 Catalina from around 1986-1989 can be had for about 50-75K. The 36 Mk2 is probably the best boat they make in this range - goes for about 90-110K. As the boats are built in CA they are more common in this area then some of the boats you would find on the east coast (sabers, bristols, etc). They hold their value better then most boats. I can give you a lot more info on them if you like.
I have recently moved up to a Passport 40. Much more living space, and a much heavier displacement. This is the boat I hope to take to New Zealand someday. I spent a lot of time deciding on the passport - I think it is one of the finest boats ever made - (considering price,quality,design,etc). They are not cheap (for me anyway). A good one will cost you at least 125K probably more.
Of course there are many other good boats for sale in the area. I recommend a subscription to 48 North, the local boating rag. It is an excellent magazine covering boating in the NW.
Living aboard a boat in Washington does have some legal problems. In the last few years, the state has been making it harder to do. Most of our marinas are on land leased from the state, and Washington has placed limits on the percentage of liveaboards in each marina. Before you buy a boat, you should make sure you have a place to put it. Marinas on the east side of the sound generally have a waiting list. The wait can take years, depending on the size of the slip. Things are a little bit better on the west side, but the live aboard issue is a problem almost everywhere. Live aboard fees can range from $25-$300/month, depending on the marina.
I know this may sound daunting, but you can generally find the space you need, it just takes a little time and effort. Again - look in 48 North, they have a section in the classified for available moor-age.
Don't forget the sales tax. 8.8% of the cost of the boat. Let me know if you have any specific questions. Good Luck.