We spent 1 night at Sant'Antioco in Bed and Breakfast Gaulos during our Sardinia holiday. I wish we could have stayed longer. It felt this island was true Sardinia, far from the touristy Costa Real and Costa Smeralda which we visited after. San't Antioco's and Calasetta's beaches may not be par to the ones at Porto Cervo and Villasimius, but this place is definitely worth visiting anyhow! The town of San't Antioco is small and charming, and so is the town Calassetta nearby, with lots of nice small pizzerias and ristorantes.
This bed and breakfast was amazing; 35 eur per person, room was impeccably clean, with own balcony and the family was soooo friendly even though their english was quite bad. It is within walking distance from Sant'Antioco centre.
Simple but very tasty breakfast was served in the sunny terrace.
If you stay at Sant'Antioco couple of days and you have a car, B&B Gaulos is excellent and affordable place to stay and explore this island.