The view of downtown Seattle really doesn't get any better than at Gas Works Park. Come here on a sunny weekend day to watch the sailboats on Lake Union, or at sunset to see the sun disappear behind Mount Olympus and the city lights come up, one by one. On a windy day, bring a kite. Be sure to check out the big funky sundial at the top of the hill.
It's a fascinating place to watch people, too. Morris dancers practice here on summer evenings, and skateboarders grind on the concrete. Sun worshippers and kite flyers are well represented.