We chose Ozieri as it's only an hour or so from the airport -- and that's its main attraction. There are some lovely winding streets, but not much else there.
If you do stay here, try the Mastino. It's clean and cheap. The rooms are dark and a bit dated, but the staff was friendly and there's a great restaurant downstairs. The spot CERTAINLY wasn't flashy, but half the town came to eat while we were there and the food was fabulous and dead cheap.