Sardinia, more than Corsica, provided various advantages to the Romans. As a military outpost, Pompey used the island for his very quick campaign against piracy.  However, Pompey must have done the Sardis wrong, because during the war between Pompey and Caesar, Sardinia supported Caesar. In 67 Nero gave Sardinia to Greece in order to undermine the senate, then in 73 Vespasian took it back because he may have thought the Greeks would use it against them.

Agriculture was also important, as the Carthaginians had been farming there for some time. The amount of grain produced there provided for surpluses in the Empire. Latifundium, or state farming, learned from the Carthaginians, was prominent.  And other than some salt and a little iron, grain was the main product of the islands.

Since very few Italians actually migrated to the islands, and it seems that Corsica was used for banishment most of the time, there are only a few cities that were completely Romanized.  There were many bath houses, forums, and amphitheaters, temples, but mostly on the costal lands.   

Tharros Bath (Sardinia)
http://www.usd.edu/erp/Sardinia/cities.htm

Nora Theatre (Sardinia)
http://www.usd.edu/erp/Sardinia/cities.htm

Map of Sardinia (Click for Larger View)
Robert Rowland