What to do in Seattle?
Restaurants: Ivar's on the Waterfront or The Fisherman, just up the
street.  Space Needle observation deck if the weather is clear.  Museum
of Flight a must if you are any kind of airplane buff.  Most people
visiting want to go to the Pike Place Market, you can combine that visit
with the waterfront restaurants I mentioned above.  Another good
restaurant is Chinooks at Fishermans Terminal in Ballard.  The Seattle
Art Museum, SAM to the locals, has gained a good reputation, right in
downtown.  Another attraction is the Seattle Underground Tour in Pioneer
Square, tours the 'underground city' that remained after the Great
Seattle Fire.
If you have local hosts to guide you, take a drive along Lake Washington
Blvd, lovely homes.
For the really unusual and related to Seattle only because it is here,
there is a now privately owned USSR Foxtrot class sub tied up south of
the main waterfront area, open to tours.
These are suggestions from a Seattle native, lived here 65 years....