>I wonder, what city has the lowest fares to/from most locations and the most inexpensive lodging?
>

Atlanta has direct flights from practically everywhere and is less than an 8 hour drive from a huge swath of the east coast.

Reader Pool for Best U.S. city for conferences:
http://www.toprankblog.com/2007/06/reader-poll-best-city-for-conferences/

Las Vegas (18%, 19 Votes)
New York (16%, 17 Votes)
San Francisco (15%, 16 Votes)
Chicago (10%, 11 Votes)
Seattle (9%, 10 Votes)
San Jose (6%, 6 Votes)
Boston (6%, 6 Votes)
New Orleans (4%, 4 Votes)
Austin (4%, 4 Votes)
Minneapolis (3%, 3 Votes)
St Louis (3%, 3 Votes)
Dallas (2%, 2 Votes)
Miami (2%, 2 Votes)
Washington D.C. (2%, 2 Votes)
Denver (1%, 1 Votes)