Seasons

Shoulder season is amost always the best time to travel anywhere: better weather, less crowded. While prices may not be lower, there is less competition for the best values.

We never travel is summer, so I too would avoid the summer heat, mosquitos, crowds, extra tourists in Italy.

Spring (late April/early May) is nice because the spring flowers are in bloom. That may not be too important in Rome or Venice.

Anything after Sept and before late May.

If there's no reason requiring you to go in the summer (school age children, teaching jobs), it's best to avoid the hottest and most crowded months of July and August.For the best combination of not so stifling weather and somewhat fewer crowds, many think September to early October is best, or mid-April to mid-May.

I'm sorry, I've not heard the term shoulder season?