I think you should check several for your own taste in how you wish to work an interface. Travelocity used to be extremely nimble for my purposes but I hate their redesigned interface. Many sites have their own approaches to walking you through reservations. One note: test some prices. Last winter Travelocity sold UA flights to europe for $50 less than the UA site (UA=$314 and Trav=$264, same flights, same days, same base fares. Go figure).