I had never used one of the airline "aggregator" sites such as Kayak.com. My niece had a stroke, and my wife needed to make an immediate airline trip to be with her and her sister. Looking at the regular airline sites, the same day fares were $500; we were looking at this after midnight, and my wife needed to travel that same day.
So I went to Kayak.com, and it showed me many fares in the under $200 range, for the next date date. It appeared that Alaska Airlines had a $170 fare for the same day. Kayak took me out to the Alaska site. I carefully booked the flight, and paid. The flight was a commuter flight from our home airport to a major airport, and then a regular Alaska flight to our destination city.
One "odd thing" happened - when i signed up for flight alerts, it would not give me a flight alert for the commuter flight...the Alaska site did not explain why, and it gave me an alert for the second flight.
My wife went to the airport (it's now about 8 hours after the ticket booking). When she got there, she found the Alaska counter empty, and a sign saying that the commuter flight she was looking to board was not even scheduled until next month. She called Alaska, and they 'discovered' that we had booked a flight for 2 weeks from today!
How did Kayak "transfer" my request for a January 29 flight into an Alaska Airlines response for Feb 12? This tells me to BE VERY CAREFUL when dealing with a "cheap flights" web site.
Alaska Airlines was very gracious, and booked the same itinerary for about 4 hours later for the net fare change without further penalty. Of course that was more than twice what we thought we were going to pay, but still less than what I had seen on the United and Alaska web sites. My compliments to Alaska