I am trying to coordinate flights over the xmas/new years holiday. It involves flying between 3 cities, and the middle city might change depending on pricing and timing.

Does anyone know of any good sites for picking these flights? I have tried Expedia and Travelocity but those are sometimes hard to manipulate. I tried USair.com but of course that site sucks and they do not always give you the best price. Any ideas would be greatly appreciated. Thanks!!!

P.S. On a side note...how is Toronto for New Year? I have never been there before.