Bill and El,
We also have some cruising the South Sound info that we'd be happy to share with you at Bellingham.
Agree with the previous suggestions and will add a few more in a later post but for now, must see place probably include Gig Harbor (as mentioned) and Poulsbo.
Gig Harbor has very limited transient marina space (basically Arabella's Landing) plus a nice but small public dock - usually full. However, you asked about anchorages and Gig Harbor is small, crowded sometimes but it's only about 25 feet deep all over and there are always places to anchor. Gig Harbor is kind of a touristy place but nice to visit.
Poulsbo has a very nice public marina with about the best price for fuel in Puget Sound. It's a very cute little town with a definite Scandinavian flavor. We like Poulsbo a lot. There is lots of anchorage available near the marina which is right downtown.
If you want a really different experience, I highly recommend Bell Harbor Marina in Seattle. It's a very secure public marina - not very large but it's right on the Seattle waterfront. Easy walking distance to the Pike Steet Market - very much worth a visit and long but doable walks to everything from the Space Needle to Seattle's Chinatown. You will need reservations (probably) and you will probably be the smallest boat in the marina (we've been there several times and have always been the smallest) but it's definitely a must see. By the way, when we've been there, the restrooms and showers were exceptionally well cared for - which was nice. It's possible, I suppose, but I've never considered anchoring in Elliot Bay.
Just outside of Seattle, across Elliot Bay, is Blake Island. Blake Island is primarily a marine park although one of the local Native American tribes has a lodge there and there are daily boat trips from Seattle to salmon dinners at the lodge. Nice, minimal facility state marina. The island has a lot of trails for hiking. We've never tried anchoring there but have seen boats anchored at the southwest end of the island. It is awfully exposed, however. There are quite a mooring buoys and that's what we've used. Can be bouncy because of traffic.
More later,