You did not mention budget, or the desire to have short travel time, but I believe that nothing beats Hawaii for a conference. Our company has had "retreat conferences" @ the Hyatt Regency on Kauai and the Ritz-Carlton on Maui. Both first rate properties with golf and other activities close by. On the mainland you may consider the Westin La Paloma near Tuscon (another very nice property) or the Sheraton @ Torrey Pines just north of La Jolla. Our company has also used the Ritz-Carlton in Naples, FL which is also an excellent property.