Hi--
I lived in Seattle for 5 years, and now live in Eastern Washington. I'd be glad to help anyone out who has questions on staying in Seattle. I agree with above, that Pike's Place Market is great. Also, if you are a family, consider taking the monorail from downtown to Seattle center (about 3 miles), where there is a science museum, children's museum, the Space Needle, and Experience the Music Project. Also, the shopping downtown is fabulous, as well as tons of fabulous restaurants.
As to where to stay, any of the higher rated hotels in Downtown would be good. To me, where to stay would depend on what time you are arriving the day before. If it is after 5 pm, by the time you get your luggage, etc., I would just stay near the airport, and then get a shuttle or cab to downtown the next day to catch the cruise. The reason I say this is that the downtown attractions pretty much close up by 6 pm, and it wouldn't be worth the extra money staying downtown. The airport area is much less expensive. There are also several good restaurants near the airport and hotels, as well as a very large mall not too far away.
Hope this helps. You can e-mail me with more questions, or post them on the site here and I'll try and check back.