Although I am not an opera lover, if I were, going at least once to the festival at the Roman Arena in Verona would be among my highest priorities. Verona is a very beautiful city in its own right, conveniently situated near Milan and its international airport, and not far from Venice. It is also very close to my favorite Italian lake, Garda.
The 86th edition has been on about a week now and will continue until the end of August. Here is a site which is in Italian only but has interesting videos on the history and productions of the event that can be enjoyed even if you are Italianless. The Arena's own site is also in English, with the complete program (heavy on the Verdi, as always) and booking capability for tickets and hotels.