I'm planning a trip to Italy for either the first half of June or the last half of July. Itinerary would include: Venice, Cinque Terre, Rome and Sorrento. The last time I went to Italy was in December 2012 (Rome and Amalfi Coast). While the crowds were very light, the weather was very chilly. The time before that, I went in September 2006 and the weather was spectacular! (For that trip, we were in Naples, Rome, Cinque Terre and Venice). This time, I have to work around the school year, so summer it is. From what I understand, June weather should be similar to September so that is my first choice. My concern are the crowds. I've read June is more high season than July in Italy. How crowded are the main tourist sites in June vs July? Is there a big difference? Thanks!
Crowds will be about the same (Venice or Rome) to much worse (Amalfi Coast and Cinque Terre) in July. The weather in July is the hottest in the year, so possibly unpleasant to walk around the streets, especially in the early afternoon. June is preferable in my opinion. Actually the earlier in June, the better, IMAO.
June would be better weather and less crowds. Not sure why you think June would be more crowded than July?
Go with June.
As mentioned, the earlier in June the better. The crowds will be big in either June or July.
Visit in June for better weather and less tourists. Start in Venice and move south because of the difficulty departing Venice in the early morning.