Where (or what country?) are you coming from?

And yes, there are a lot of good things to do in SF more so than the Silicon Valley. Let me know what your interests are, i can point you to a few good things. If you know people (maybe you can meet them here), visiting the google campus and/or yahoo campus is always a treat. Not sure if Facebook has anything exciting to offer, but i know their office space looks nice.

If you want to visit something techie/educational, the exploatorium is fun, academy of science is great. There are more good eats in sf than sv (imho).