http://travel.usatoday.com/experts/...Fi-Airports-explore-tiered-service/48413614/1 For years, one of the top if not the top amenity on many road warriors' wish lists has been free Wi-Fi at the airport. Slowly but surely, it's happening. Take a look at the USATODAY.com Airport Guides, airport websites, and various commercial and user-generated Wi-Fi directories. You'll see there are now hundreds of U.S. airports offering travelers complimentary wireless Internet access. San Francisco? Free. Orlando? Free. Seattle, Sacramento and San Jose? Free, free, free. Washington's Dulles and National airports? As of April, 2011, free as well. Free Wi-Fi sounds great. But during heavy usage times at some airports, service often slows down. And some free airport Wi-Fi has strings. Most often, it's in the form of advertising a user must view before getting online. At Denver International Airport, "Sometimes it's a session sponsorship, such as a video and then users are directed to the internet," said DIA spokesperson Laura Coale. "Sometimes it is banner ads." At Boston's Logan International Airport, where 198,000 free Wi-Fi sessions were logged during May, travelers must click through to a second screen before they see the button offering free Wi-Fi. "The user agrees to watch a short commercial or take a survey to gain access to the free site," said airport spokesperson Mathew Brelis, "That times out after an hour and they need to log back on again." There remain some holdouts. Notable among airports that only offer paid Wi-Fi (outside of airline club lounges) are Hartsfield-Jackson Atlanta International Airport, Minneapolis-St. Paul International Airport, Newark Liberty International Airport, LaGuardia Airport and JFK, except for JetBlue's Terminal 5, where complimentary Wi-Fi is offered as an amenity by the airline. There's a plan underway to provide free Wi-Fi at Los Angeles International Airport within a year.