Seattle is surrounded by water and mountains and the citys attraction lies in not only the stunning views from the top of the Space Needle, but also in the natural landscape surrounding it. The waterfront and the neighboring Pike Place Public Farmers' Market still are a must for both locals and tourists. Here you can find the famous fish throwers, fresh produce and many quirky shops located directly under the market. While you're at Pike Place, keep an eye out for the original Starbucks. On rainy days, go to one of the museums such as the Seattle Art Museum, Seattle Asian Art Museum, The Henry or the Frye Art Gallery (among others). The visual arts are plentiful in Seattle, so don't miss a chance to see the Pacific Northwest Ballet, the Seattle Opera House, or any of the number of plays and comedy acts strewn throughout the city. There are also fringe movie theaters such as the Egyptian in Capitol Hill and the Grand Illusion in the University District which show more artful and sometimes older movies than the standard theater shows.
Also worth investigation is the Underground Tour. Seattle had great fire in 1889, and 33 blocks burned. It was too much work to tear down and rebuild, so the people just built the city on top of the old one, and a layer of the city can still be seen intact beneath the street.