Well, one summer I discovered Sicily at the D&G boutique in Milan, and I have associated Italy in summer with that scent ever since. It just works: it's blousy, it's fun, it's fruity, it smells like gelato and fine clothes, and it's totally vampy.
Another favorite I always associate with Italy in summer is Fred Hayman's Touch. A thick-yet-breathy floral with a sultry side. Like the hydrangeas and flower gardens on the hillsides mixed with the smell of brown sun-baked beach skin.
For the night time there in summer, I recommend Gianfranco Ferre's Ferre by Ferre...or anything else by him; all his scents evoke stars at night. The star-filled sky is massive, ancient, infinitely celebratory and truly the pillow of the world.
Have a great time! Whatever you wear, you cannot go wrong enjoying an Italian summer !