In Seattle, if you haven’t been to Pike Place Market, it’s worth a visit. Museum of Pop Culture isn’t too far from there (at Seattle Center, which also has the Space Needle) and usually has some good geeky fun happening. Also downtown, if you need to get off your feet or out of bad weather, Cinerama is a terrific place to catch a movie.
Seattle Eater is a great site for checking out the local food scene – look at their Hottest and Essentials lists. We’ve got a few local star chefs here who have multiple restaurants – look up Ethan Stowell, Renee Erickson, Rachel Yang, and Tom Douglas.
If you are interested in getting out of downtown and exploring neighborhoods, you could hit NW Seattle and visit Ballard and Fremont. Both have lots of shops and restaurants. Ballard has more bars (and Full Tilt ice cream + pinball), Fremont has a Lenin statue. Outdoors, Ballard has the Locks and Golden Gardens beach, and Discovery Park in Magnolia is close by. In Fremont you can hang out by the water at the Cut or head over to Gasworks Park.
East of downtown, Capitol Hill is a lot of fun, and there are at least a couple makerspaces there along with a technical bookstore. Volunteer Park is lovely, although the Asian Art Museum is closed for renovations. Lots of restaurants, bars, and clubs. If you continue east from Capitol Hill, you can go to the Arboretum and the Japanese Garden (and, ultimately, Lake Washington).
Hope that helps get you started – sounds like a great trip!