Tucked away on the Stanford campus, Cantor Arts Center is sometimes overlooked on the local museum circuit. The third largest collection of Rodin sculptures anchors the permanent collection. And it's all free... always!
Andy Goldsworthy's 'Stone River' (Goldsworthy also has a piece outside the de Young Museum in SF) and the Papua New Guinea sculpture garden are worth a peek as well. For more campus artwork, check out the art buildings to the left (south) of the main quad approaching from Palm.
For even (!) more, check out Laura and Kevin's unofficial guide to Stanford :)
Address: Museum Way and Lomita Dr, Stanford, CA
Website: http://museum.stanford.edu
Wikipedia: http://en.wikipedia.org/wiki/Iris_&_B._Gerald_Cantor_Center_for_Visual_Arts