I also loved the fact that you could enjoy the beaches all by yourself. I love to explore abandoned buildings, although the old resort that I found was fenced pretty well and full of camera's.
The contrasts are insane if you look to what's happening during high season. The climate isn't that bad in winter, you can still lay down in your swimwear and take a dip in the crystal clear waters. I know who to contact next time I am there in winter haha. Which area of Sardinia are those 2 apartments?