90% of my travel is done through a travel agency. I tell them is when I want to leave and come back. They book the cheapest flights and cars. They usually get better deals than I would get booking through a site myself. The only thing I dont normally go through them for is hotels, I get a much lower rate than they can get.
Its much more convient if you travel a lot, you dont have to worry about anything. If anything happens en route or if I have to change my flight one call and its taken care of. I dont have to wait on hold.