Originally Posted by ND Sol

That's making the assumption that there is even free wifi:

Looking at the top 15 airports from what I can find:

1. Hartsfield Jackson Atlanta International Airport ATL - No
2 O'Hare International Airport ORD - No
3 Los Angeles International Airport LAX - No
4 Dallas/Fort Worth International Airport DFW - No
5 Denver International Airport DEN - Yes
6 John F. Kennedy International Airport JFK - No
7 McCarran International Airport LAS - Yes
8 George Bush Intercontinental Airport IAH - No
9 Phoenix Sky Harbor International Airport PHX - Yes
10 San Francisco International Airport SFO - Yes (only started a year ago)
11 Charlotte/Douglas International Airport CLT - Yes
12 Newark Liberty International Airport EWR - No
13 Orlando International Airport MCO - Yes
14 Miami International Airport MIA - No
15 Minneapolis-St. Paul International Airport/Wold-Chamberlain Airport MSP - No

That means that 60% don't have free wi-fi and none of the top four do.