Are you flying to Alghero? If so there is the Soleado Hotel on the seafront - not bad for a 3 STAR. Nice rooms, clean, swimming pool. We were there for a week this month . Alghero is lovely. It is quiet - but busy. Plenty of good restaurants and old buildings to see. No rowdy drunks or anything like that - mostly Italians. October could be quieter - but you might get a table at a restaurant quicker than in August.
You could try "Just Sardinia" - a UK based agency - we booked through them and they have selection of different accommodation and locations.
www. justsardinai.co.uk