Inform your wedding party you are planning a destination wedding, then ask them to stand up for you, this way they can decline without being embarrassed. Notify your immedaite family and good friends of your destination wedding, so they can get the best deals on flights or budget for gas. Send out invitation at least four months, but better - eight months in advance. Not everyone knows protocol about wedding invitations, so don't be upset if some of your closest friends or relatives don't return the reply card or don't show up at all.
Destination Weddings are not for everybody. The cost, while you are, in a sense, footing the bill for the food and the venue. They too, will have their fees for travel, hotel and car rental and that adds up.