I read your post (finally)- check into my "Koffee Brown Goes to Italy" section to read about my tour in Italy.
Italy will be pretty hot starting in late June, so try to start early in the day and take A LOT of water and take breaks whenever you can. That's about the only caveat I have for you about Italy.
I loved Italy- I cycled in the north, the south, and the west parts of Italy. I never had a problem with the traffic. Naples seemed to be a little hairy, but otherwise, I had a blast. The cars always yielded to me- I was a bit surprised that they would stop and wait for me to pass or try to outrun me to turn right when I was on the roads or whatever... they treated me with respect and courtesy, as if I were part of the traffic! To tell you the truth, it freaked me out a bit in the beginning. The first time I noticed this was when this woman was waiting to pull out of a parking lot. I was approaching, and I wasn't going very fast either. In Chicago, where I live, I'm sure the car would have tried to beat me out of there, but in Italy, the woman waited patiently. I slowed down even more in anticipation of the car turning in front of me, but the woman waited and smiled at me. I finally got it- she wasn't going to turn until I passed, so as I passed, I waved and mouthed a "Ciao" at her. She waved back and I went on my way. This is just how it was.
Not only was the traffic pretty courteous to me, there are so many people out there cycling, that it's impossible for you to even believe that traffic is not used to seeing people on bikes. I often ran into groups of cyclists, and they always said "ciao" or "bonjourno" or some kind of greeting when they passed. I felt a real sense of community with the cyclists out there. I got the shock of my life one day when I was riding my bike and all of a sudden, some guy comes up from behind (in Como) offering me his water bottle, screaming "ciao!". I laughed and we cycled side by side for a few moments as I showed him my water bottle and said thanks for the offer. He wished me a good day and kept on going. That really made my day too- I'd been travelling for hours and hours by myself, and it was a nice break from being alone.
Gotta get to work, but you can PM if you're looking for more details on travel in Italy.