Hi, Elizabeth -
I live not far from the Silver Cloud Inn. It seems nice (although I have not been inside) and is close to a number of restaurants along Lake Union. Although not downtown, it is on a bus line, so you can easily get into the city. I notice they also have a van, so I assume you could get transportation to airports, docks, etc.
Although you will be here before and after a cruise, I do suggest taking one of the water tours of Seattle. There are a number of routes from which to choose.
Another way to see a good deal of the city in a short time is to take one of the Duck tours. These tours use WWII Ducks (amphibious vehicles)so you get a road AND water tour. It's a little like riding a truck into the water, but fun nevertheless.
The Market and the locks are both interesting and unique, and I agree with John that Ray's is a good place to eat. Another restaurant in the same area is Anthony's Home Port, especially nice for a weekend breakfast.
My favorite waterfront restaurant in Seattle is Ponti, next to the Fremont Bridge. It's walking distance (a mile or so) from the Silver cloud, or you can catch a #17 bus. (That same bus will also take you all the way to the Ballard Locks, btw.)