Over at the Mercury News site, Ethan Baron has a fun story on tourists who travel (sometimes from other countries) to Silicon Valley to visit big companies such as Apple, Facebook, and Google. None of these places are set up to welcome civilians, and all are security conscious, so the visits usually don't amount to much more than posing in front of signage and maybe buying a tchotchke in a gift shop.
As the article conveys, Google's campus is at least a tad more tourist-friendly than most: The giant sculptures of Android mascots are on a public thoroughfare and well worth a visit. The local color also spills out onto the streets of Mountain View, where every motorist gets to experience the novelty of dodging Googlers on colorful bikes.
But really, if you've traveled to Silicon Valley to learn about Silicon Valley, my top recommendation would be to visit the wonderful Computer History Museum. It practically adjoins Google's headquarters—and like the core structures at the Googleplex, it's a repurposed building from once-mighty tech firm Silicon Graphics. HM