In some cases, travel agents can set up packages slightly cheaper than one might find on the net. But, doing the research yourself can often help you locate feedback about a particular place that isn`t travel agency biased.
For instance: I took my girlfriend on a Blackbeard`s cruise in the Bahamas in January and did the research myself. We stayed in a little out-of-the-way place on Blackbeard`s website. We heard several horror stories about folks who stayed in up-scale hotels for up-scale prices. Even though we didn`t stay up-scale, the service was beyond fist rate. It influenced both of our attitudes toward the trip immensely.