The 2003 PDC was my 5th PDC.  I'm usually pretty hard core about absorbing as much as I can but the 2003 PDC pushed me to my limits.  I rarely ate in the eating area.  It was usually gotten to go so I could run off to the sessions scheduled during lunch.  My first suggestion is to *not* schedule sessions over lunch.  Give folks a chance to take a breather and talk to other attendees over lunch.  My second suggestion is make the wireless network more reliable.  Finally, I enjoyed previous PDCs where there was a PDC mailsystem that allowed you to find other attendees (folks you might not have seen in a while).  In general Microsoft puts on great conferences ('98 PDC excluded) and takes good care of the attendees.

PS. I loved the Snickers Ice Cream bar snacks!  Yum.