I agree with dolcevita - the Marriott Residence Inn on Lake Union is very nice. Spent many nights there in the process of moving to Seattle 2 years ago. Be sure to get a lake view room.
We rent a room there for the July 4th fireworks on the Lake and invite a few friends. The location is not downtown but I think they run a shuttle.
You will be too late for copper river salmon but the seafood is very plentiful and guaranteed fresh. Outstanding restaurants. Although I have not yet been, I am told the Experience Music Project is quite a treat although a bit expensive. On a nice day, take a ferry to Bainbridge. The return to downtown is beautiful and the ferries are spectacularly well maintained.
For a nice lunch or dinner, go to Maximillien's (in Pike Place Market - a bit hard to find but go just ot he left of the fish throwers. Small restaurant with great views of the harbor.
You are in for a treat - if the weather cooperates.