Tilden Regional Park: There is a 10 acre Botanic Garden in the Tilden Regional Park. There are ten sections to represent the ten different regions in California.
University of California at Berkeley: The beautiful campus has a number of sites to see including the Bell Tower, a fantastic children's science museum, and often holds concerts and the like.
Lawrence Hall of Science: Perched on the mountains to the east of town, on the UC Berkeley Campus, is the Lawrence Hall Science Museum. This museum is a great place to take kids and has a number of kid friendly displays.
Sather Tower: Is one of several buildings on the UC Berkeley Campus listed on the National Register of Historic Places that are well worth seeing.