I think ITN and Travelocity will give good guidance, but my experience is that it is best to understand potential connections and fares on various routes. Once you begin (by trial and error) to understand the fare soft-spots -- both origin and destination, as well as connection, you can then create an itennerary, using MULTIPLE DESINATIONS on Travelocity or ITN.

For example, I will be flying between Virginia and Boston over the next few weeks. I have found that since Metrojet flies ATL - BOS, that I can book very affordable fares, during certain times of the day from Norfolk to Boston via Atlanta on either US or DL. Also, since US Air Shuttle started service out of Wash-Dulles, the fares from IAD - BOS are quite affordable on either US or UA.

Another sweetspot I found is on SwissAir. SR is offering $330 flights from IAD - ZRH. SR will also fly to Rome or Milan with a connection in Zurich for another $150, and will allow stop-overs under 24 hours. I was able to book a trip to Milan, with a day in Zurich and a day in Rome for $488, which included 6 segments, and with credit on Delta, I get 6 segments credit on DL with over 20,000 miles credit (with my Gold Medallion bonus), so I almost get a free trip with my three city tour, all under $500.

Good luck.

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