Gas Works Park is a Seattle must-see. It has an amazing view of downtown from across Lake Union, a large hill with a beautiful sundial at the top, and, of course, a now-unused natural gas extraction facility (it's sealed off but still something to see). Gas Works is considered prime viewing for the WAMU Family Fourth celebration, each year on July 4th. During the period of the first Gulf War, Gas Works was the site of the PeaceWorks Park vigil. If you bring a laptop (or other WiFi capable device), there is free wireless provided by SeattleWireless.