Another great place in downtown Seattle is Pioneer Square.  It is about half a dozen blocks south of Pike Street on First Ave.  This was the original center of Seattle.  There is a nice park with a steel arch canopy.  The night life in this area is great.

There are a lot of restaurants in the Pioneer Square area, most with outdoor cafes.  You can also take an interesting tour of Underground Seattle in which you explore the history of the city though a maze of passageways beneath the sidewalks and buildings.

For history of a different sort, take a boat from the waterfront out to Blake Island in Puget Sound (about a 45 minute trip with some beautiful views.)  Blake Island is now a state park featuring Tillicum Village, a restored Indian settlement.  There is a lot to see.  The $20 charge incluldes the boat ride, a native american program complete with story telling, dancing and costumes, and a great meal of salmon baked in the traditional indian method.