We are exploring a class of decision-theoretic handheld systems that give a user personalized advice about how to explore an indoor area in search of products or information. An initial user test in a simple mockup of a shopping mall showed that even novice PDA users accepted the system immediately and were able to achieve their shopping goals faster than when using a paper map of the mall. A key issue is the extent to which spontaneous user behavior can be accommodated within this framework.