Unless you're able to rent a private home with beach front property, the beaches of Hawaii and Mexico are not going to provide much in the way of seclusion. Luckily, less common tropical destinations will grant a more private vacation. Islands in French Polynesia, such as Bora Bora or the private Le Taha'a, are harder to get to and thus more exclusive. The beaches of Thailand and Fiji also offer a more secluded experience.
Like remote islands, mountain destinations require more travel effort than a simple direct flight from one major city to another. Mountain lodges and cabins offer secluded vacation options that range from high luxury to rustic experiences. Both the Smoky Mountains of Tennessee and the Rocky Mountains (Canadian and Western United States) offer many forms of accommodation in remote locales. If you choose to rent a private cabin, you can literally spend your entire vacation without having to see anyone.
If hot weather is not your preference but you want to experience some privacy in a coastal location, many United States and Canadadian private homes are available for rental on the coasts of Northern California, Oregon and Washington state. British Columbia, with its long coastline and abundant islands, offers numerous secluded spots, most notably the Gulf Islands and the Sunshine Coast (on the mainland but accessible by ferry). On the East Coast, Maine and New England offer secluded coastal locales. The Canadian Maritime provinces also offer a host of affordable and secluded rental homes and bed and breakfast inns.
The seclusion of the American plains and prairie also makes for a unique vacation spot. Many working ranches and farms across the American heartland offer accommodations for tourists. These locations offer vast fields of land and blue sky with very few other people around.