Flagstaff has an airport but it is a regional airport, called Flagstaff Pulliam Airport, so flights may be limited. The Phoenix Sky Harbot international airport is most likely where you would catch the smaller flight into Flagstaff.
There is quite a difference in elevation between Phoenix and Flagstaff and some people are sensitive to that change -- headaches, dizziness. If you know you tend to get these elevation-related problems, please be prepared.
You might fly into Phoenix and rent a car. Driving to Flagstaff is approximately two and a half hours from Phoenix.
Arizona Shuttle offers a van shuttle service between Phoenix Sky Harbor Airport and Flagstaff: http://arizonashuttle.com/schedules/flagstaff-phoenix/ Cost is about $45/per person per trip; total would be $90. It is a 3 hour trip.
Avis Rent-A-Car is offering special rates for all attendees of the CALICO conference. For reservations call your preferred travel agent or call Avis at 800-331-1600 or access Avis online reservations. Mention AWD # J992311 to receive these rates.