There's the Tech Museum downtown, the Children's Discovery Museum, the Quilt Museum, the Rosicrucian Museum (Egyptian mummies), the Winchester Mystery House. I take people to see Fry's Electronics (the Egyptian themed one in Campbell). The Lick Observatory is on Mount Hamilton. There's the Cantor Museum at Stanford. You just missed the tennis tournament at Stanford (Serena won). Just this Wednesday Cavalia is opening under the big top near 101 and 87. Also in San Jose is Santana Row shops and restaurants.
If you want you can tour Intel in Santa Clara, or visit the theme park Great America.
If you drive for 45 minutes over the hill you can go to the beach in Santa Cruz and watch the surfers by the lighthouse, or visit the surfing museum, or ride the Giant Dipper at the Boardwalk.