Rule reminder
Large islands use 'in' (in Sicilia, in Sardegna, in Corsica). Small islands use 'a' (a Capri, a Ischia, a Malta). Cities always use 'a'. Institutions without an article may use either 'a' or 'in' depending on the noun.
Passiamo le vacanze ___ Capri. (We're spending the holidays in Capri.)