Gilroy Garlic Festival
July -- Gilroy Garlic Festival, (http://www.gilroygarlicfe...). The country's largest festival devoted to everything garlic. Garlic plushies, garlic ice cream, garlic weavings, garlic wine, garlic-till-you're-sick. The last full weekend of July.
Gilroy Gardens
3050 hecker pass hwy, +1 408 840-7100, (http://www.gilroygardens.org). open from mid-spring to mid-fall. a theme park whose theme is plants, agriculture, and local history. best for people interested in gardens, and for families with younger children. like legoland, the rides here do not cater to teenagers or older.
Chitactac-Adams Heritage County Park
(http://www.sccgov.org/por...) is an interesting little park where the ohlone people lived for several thousand years. it's not a destination by itself, but if you're in the area ...
Visit some local wineries.