The precise building and room locations of UAI-2000 Events (and those joint events with COLT-2000 and ICML-2000) can be found on the
For information on accommations, please see the UAI-2000 Conference Registration and Accommodation Information page. (The Stanford University Visitor web page contains a list of additional hotels.)
When packing, remember that Silicon Valley lies in an arid region with a Mediteranean climate, so you will want to bring a jacket or sweater for evening wear, but probably not an umbrella. Of course, UAI participants will want to assess their own risk attitudes when making a decision to bring an umbrella!