Can I please get some help with booking a short trip to Sardinia from the mainland ? We are visiting Italy for our second (and hopefully not our last) trip to Italy. We have not seen Sardinia and are limited in the amount of things we can see, but would REALLY like to get a taste of Sardegna without spending many of our daylight hours on a ferry!! Does anyone have any experience with the overnight ferry from Citavecchia to Olbia? If so, how was your experience? Thanks!!!!

What's your question? The Civitavecchia - Olbia ferry ride takes only about 7 hrs. So you will hardly be able to sleep more than 6 hours.
Other Sardinia ferries:
Genoa - Porto Torres
Genoa - Olbia
Leghorn - Olbia
Genoa - Arbatax
Civitavecchia - Arbatax - Cagliari
Civitavecchia - Porto Torres
Naples - Cagliari
Palermo - Cagliari
Trapani - Cagliari
Bonifacio - Santa Teresa
Marseille - Propriano - Porto Torres
Barcelona - Porto Torres
hydrofoil Fiumicino - Arbatax in high season

tons of low cosst flights from all over Italy to Olbia, Alghero, Cagliari and Tortoli

If you come to Sardinia in summer there are also some fast ferrys, that take you to the island in 4/5 hours.