Cagliari is a beautiful city and the things that I would advise you to visit are the most important and main tourist who stops for a few days.
The day of your arrival you suggest going for a walk to the waterfront Poetto where, besides enjoying a bit of sea, you can see, not far from it, at Molentargius pond, flamingos from their infamous pink.
The next morning I would devote to visiting the historic center called Castle, which takes its name, in the Sardinian language, the city of Cagliari, "Casteddu" to signify precisely Castle.
This was the heart of the ancient walled city in which there are all of its key powers, called displacements: royal, ecclesiastical and military. You see, not far from each other the two towers still intact: the Tower of the elephant and close to St Pancras which the district from one end. Inside is a must to visit the Cathedral of Santa Maria with its rich crypt where the relics of many martyrs. Adjacent to the church found the Viceregal Palace, former residence of the vice-regal as well as his important administrative and political headquarters.
Coming out of the Elephant Tower, continue left, and sweep off university until you portrerà Bastion of Saint Remy where you can enjoy another fantastic sightseeing. The Bastion is located between two streets are the city's shopping center. Via Garibaldi and Via Manno. If you continue along the Via Manno scndendo arrive in Piazza Yenne, where you can stop and refrigerarvi of many in a local square in the evening which has become the meeting point of many young people. Here is the statue of Carlo Felice of Savoy with the index finger pointing the way Manno. In fact it should indicate the state highway 131, the main artery that connects Cagliari to Porto Torres wanted by the sovereign himself, and built at his expense. The statue was mounted on the contrary, however, are but Cagliari then affezinati Carlo Felice remains so for centuries. From the Largo statue was dedicated to him. This is also a very busy street for shopping! Eventually you will be off the street in Rome, another main street of Cagliari. Here you can admire the Town Hall, and leaving it behind, continuing under the arcades, you can head to the Basilica of Our Lady of Bonaria that dominates over a long, wide staircase of limestone. Not far away you will find Monte Urpinu, a beautiful park where you could go relax and see the beautiful peacocks that wander undisturbed.
These are just some of the things that I recommend you to see in Cagliari.
I hope you can enjoy and appreciate cagliari...