I recommend the Computer History Museum as well. I was pitching a geek tent when I visited. They have Google's original cluster and a Canon Cat! (among other cool stuff) And it's in SGI's old headquarters
The last time I heard this question asked, the answer was "no". Apple also won't allow you to tour their campus. I've spent time inside Cisco, NetApp, and Sun, and in addition to the fact that I don't think they tour either, I can tell you you probably don't want to bother. The truth is, most of the big tech companies are cube farms.
Yes, the most interesting thing about the offices of highly successful geniuses is that they look a lot like the offices of everyone else.
Indeed, the geniuses themselves also look a lot like everyone else, unless your definition of "everyone else" doesn't include geeks.
It's kind of like the rule that you have to judge a restaurant by the food rather than the decor: You judge a software company by the software, not the offices.
You are correct, offices are indeed boring... but server rooms and farms are a beautiful sight to see. At least at Cisco, the server rooms span the entire length and width of a usual building... it looks like it never ends.
If you know someone at Google, Cisco or any other big ones see if you can tag a tour around with them.
Lick Observatory in the mountains to the east, awesome drive up http://tinyurl.com/130crazyroad.