Pike Place Market is fun, but best during weekdays midday. There is a great Vietnamese shop that I can't remember the name of there that was featured on Anthony Bourdain. Matt's in the Market is also superb. The original Starbucks is at the north end of the market. Great downtown restaurants: Lola for brunch, Serious Pie for unusual pizza, Dahlia Lounge for triple coconut pie and doughnuts as well as food, Shiro for sushi, Tavolata for italian, Japonessa. Hit Fran's chocolates at the Four Seasons (it's Obama's fave, the sea salt caramels.... mmmmmm). Flying Fish on westlake for seafood. Drive up to Shilshole and eat at Anthony's on the deck (also seafood) or Palisade in Magnolia and see the cruise ships. In West Seattle, Salty's has a major brunch and the best bakery - Bakery Nouveau. Via Tribunali for wood fired pizza. Oh, and if you like Man vs Food, Beth's Cafe on Aurora is the site of the 12 egg omellete.
Sites: The aquarium is great. The Seattle Great Wheel is new and offers an amazing view. In Seattle Center, the science museum is awesome, EMP is amazing, the children's museum is skippable, the Chihuly Glass Museum is supposed to be astounding though I haven't seen it. The Space Needle tour is overrated but you still have to do it. Don't eat there. Take the Monorail back downtown. MOHAI (museum of industry) is on South Lake Union and is lots of fun, plus pretty to see. The zoo is very good, though a little further away. Museum of Flight is pretty far south near the airport but is amazing and has a shuttle simulator. Seattle Art Museum is great. See the library downtown for the architecture. Kids love the duck boats, but if you see a scowling lady in an Audi with a Foonf in the back, that's me annoyed with the duck boats.
Other cool sites- Crocodile in Belltown, where many of the grunge bands started off early. In Capitol Hill, Unicorn and Value Village were the sites of Macklemore video for Thrift Shop. Dave Matthews shops all the time at the QFC in Wallingford.
Hope that helps