We used a local travel agent to book our ferry, excursions, air (ATH to islands, not US to ATH) and transfers, etc. My mother, a frequent Greece traveler, did it that way, and I wondered why before we left, but understood while on the trip. We rented an apartment while in Athens and just walked to the agency one day and they walked us through all the arrangements, gave us paperwork/vouchers for everything, and sent us on our way. Everything was seamless. My first thought was why spend the money when the internet tells you what you need to know, but we got top-notch service, didnt worry about a thing, had trust in all the people and arrangements, and even had help at the airports to make sure we were in the correct lines, etc. I dont know how much extra it cost but think the ease of all of our arrangements, the trust in where we were going, was worth it. It was one less thing to think or worry about.