In truth, touring a linear accelerator probably can't be that great, because the really amazing parts are simply not easy to open to the public. But, you do get to see enough to appreciate how profoundly important basic research is to our world. You also appreciate the brilliance of the scientists at this lab. Rather than shutting the SLAC down when its original mission was surpassed by other facilities with greater power, the science team repurposed the SLAC into a new research facility. It continues to perform esssential basic research in new directions. You won't enjoy the tour if you have no clue about science.

My family (including 12 and 9 year old boys) scheduled the rare tour for the particle accelerator. It is really for 12 and older, but my 9 year old loves physics (don't ask), and Stanford was kind enough to make an exception. The tour begins with a 20 minute powerpoint to get everyone acquainted with atomic particles, etc, and then you get taken to an above-ground portion of the accelerator, the control room, etc. All in all, my wife and I, to science geeks loved it. My 9 year old loved it. My 12 year old who is more into history, debate, and literature was bored.