A greek destination wedding can be a very beautiful one on any one of the islands, however what you first have to get through is the marriage requirements. It is very important because there are extra steps that a U.S. Citizen has to go through, like translation of all documents into Greek approved by a consultant, Single Status Letter and the Apostille from your state. Plus some of these destination weddings are not being accepted by local goverment officials. You have to be very careful with that. Check with your local DMV and state to see if they accept that documentation to change your name.
I will be honest to say that we do not do a wealth of legal weddings for Greece because of the steps in the requirements. What many couples are doing with an interest in Greece is to have a legal marriage, sign the marriage certificate at your local court house then do what is consider a spiritual wedding at the destination. That way you forgo all of the legal requirements, your family does not need to know and that date in Greece will always be your date.
If I was to pick my favorite then I would say Santorini. The beauty around this is great for pictures, the sunset here is especially nice and it is just a different way of life. And don't forget that the time of the year is going to help you make a choice too. Some of the smaller resorts on these islands are not open all year round, many close between November - April. And that also includes the ferries schedule. When I went to school over there for a year there was a couple times we got stuck on an island during that time because they did not sell enough tickets on the ferry or they just up and cancel at the last minute. I think April to June 1 and November are the best time to see the islands. You don't have all that summer traffic and the bigger cruise ships are not in that area yet. You don't want your wedding at an island when a cruise ship is to dock because it is very hard to get around town.
Speaking of getting around, I would opt for the donkey ride side saddle to the wedding. I know it sounds like an insurance policy, but it is how the locals get around and really worth incorporating as much local flavor as possible.
I hope this helps! Keep us all posted here.
Best Wishes on your special day!
Take Care,
Lindsay