We found that most Italians speak English. Clerks at the hotels, waiters, shopkeepers and everyone we interacted with, all spoke English at least well enough to carry out their normal busniess interactions. If you went off on to a different subject than their norm, then often, communication in English was a problem.. When we were off the beaten path (when we were lost south of Naples) we ran into some who knew no English. But when I asked "Mi indichi la via per Sorrento?" they understood and were eager to point the way. Another incident of note in Florence: we were on a city bus, looking at our map to determine where to get off when a woman about to leave the bus noticed us, asked where we were going, and then told the bus driver (who only spoke Italian) to let us know when to get off - which he did when we reached our stop.
Most (perhaps all) signs in the airport are in both Italian and English. Sometimes signs are in English only. I never once saw a sign for gabinetto (toilet), instead it was "toilet" or "W.C."
On the tours, the guides spoke either English only, or English and 1 or 2 other languages.
I should mention somewhere that the food was great. From the continental breakfasts at the hotels, to the sidewalk cafe's, to the sandwich shops, the food was always fresh and delicious.
The only problem we had was finding our way when not on the Autostrade (superhighway). To say that roads are not marked well is an understatement. During the hour ride to Sorrento, once we got off of the Autostrade, I think I saw a sign telling me the route number only once (maybe twice). Forks in the road have only signs pointing direction to towns, and sometimes have no signs at all (once I picked the direction based on where a bus went - figuring that if a bus came from that direction, it must be a main road). And not knowing the area, we couldn't tell if the names on the signs were towns or hotel names or names of parts of towns (this way to the beach?). Navigation was so difficult that we cancelled our planned visit to Paestum and Anzio - it was just too frustrating.