There is a lot to do in and around Berkeley, and of course an endless array of options if you include the rest of the Bay Area. Locally, we can recommend:
Downtown Berkeley – The area around the meeting venue is known for its restaurants and theater scene.
Gourmet Ghetto – No more than a dozen blocks North on Shattuck from downtown Berkeley, the Gourmet Ghetto is the home of Chez Panisse, the Cheese Board, the original Peets Coffee, and other landmark food places.
Telegraph Avenue – Still home to some great music and book stores, it is otherwise struggling to find itself after the end of the 60s, but still shows signs of its past life as the epicenter of counterculture Berkeley.
Further afield, you can find the Berkeley Rose Garden, the Lawrence Hall of Science, Tilden Park, the Berkeley Marina, and other places to wander around. The Wikipedia entry for Berkeley has good coverage of most of these options.