Just returned from Italy with the RS Venice, Florence, Rome tour. It was my 4th with ETBD, and it was perfect as usual. A few tips I wanted to mention.
Really, really prepare for heat and humidity. We knew it would be hot and air conditioning slim, but it was really relentless. Ladies, sundresses are perfect right now. I was really happy I took wet wipes, but wished I'd had a bandana or something to wipe the sweat off. Definitely take advantage of the siesta time to rest during the day to get away from the crowds and heat. Don't worry trying to "fit in" in these big cities. Wear your sneakers if you want to- plenty of Europeans are! My husband really like the pants that zip off the legs- good for churches. Eat lots of gelato because it cools you off and it's just good. The buses in Rome smell absolutely disgusting on a hot day when they are crowded...Try to use some Italian greetings and phrases. They love it and you will be much more well received. Do all the research you can- it pays off.
I realize these are random thoughts, but I'm still recovering from the 10.5 hour flight yesterday. Please feel free to PM me if you have specific questions about the RS tour.