I'd just hang out eating scary doughnuts myself, but I guess that goes without saying...
You know it's a big book store when they hand you a map of it when you walk in. Powell's City of Books http://www.powells.com/
The parks are great. Forest Park is practically endless with lots of cool trials, and don't forget Portland's Japanese Garden. Bridges everywhere, and always swarmed with people on bikes in the summer.