Easter is coming up. If you celebrate the holiday, it might be fun to do a group egg hunt rather than your own at home (or you can do both). Easter egg hunts are scheduled all over the Bay Area, including Berkeley, Oakland, Capitola, Felton, Folsom, Petaluma, and San Francisco (though the Union Street parade/fair isn't actually an egg hunt, but has other fun stuff).
Travel is More Fun with Kids has an awesome list. Check it out here.
BeachCalifornia.com has some too. The egg hunts are primarily April 3rd and 4th.