I heard an episode of RadioLab about Laughter recently. They did a fascinating job of covering the topic from multiple angles. One item stood out for me, though. They said laughter is a social thing, and that people don't laugh alone. This doesn't mean when you're watching Letterman...
With its picturesque villages nestled into seaside cliffs, its Old World love of laughter and culture, and food that makes your soul stand up and sing; there's really never a bad time to go to Italy. Except maybe during the month of August.