Do you book everything directly yourself (flight, hotel, etc) or do you buy those packs in the travel agencies that include everything? I always check the prices myself but sometimes it's even cheaper to book through a travel agency so I go with whatever option is cheaper, since it's the same flight and hotel, it's the same experience, might as well save a little.
I use the online travel guide sites such as Travelocity. I find that they always offer exclusive deals that i cannot find anywhere else. I have saved a lot of money withe them over the years. The price difference is dramatic.
I always book myself because I do not trust on any especially for the travelling because many scams is happening and I already book the hotel, rooms and manage all the tickets myself before go to the tour.