We (6 persons) spent 2 wonderful late-summer weeks in Santa Teresa di Gallura. Patrizia and her husband were very welcoming and made our stay a pleasure.
The villa is really spacious, tastefully furnished and very well equipped (great kitchen!). Each bedroom has its own bathroom, which is very comfortable. You can also rent bedclothes and towels for a reasonable price. What we enjoyed very much were the long evenings on the large veranda, having dinner, watching the moonrise...
Many beautiful beaches are nearby and you have the choice of all the right places for bathing, snorkeling, or surfing. If you like walking, there is a nice costal path you can stroll along south for hours - so make sure that someone picks you up then ;-)