I have been to Infinite Loop. I did not go for any tour. I just drove around the campus, went to the company store and got a bunch of stuff, and took pictures. There were a few other people there too. They are used to it.
Be ready to see lots of expensive sports cars. Very... very expensive sports cars, being driven into the parking garages under the buildings.
BTW, if approaching from the south (I think), the campus sneaks up on you on the right side of the road. Just be ready to turn.