I cycled around Tuscany and Umbria a few years back and had a ball- no cycling infrastructure to speak of, but plenty of quiet roads and drivers were very considerate of cyclists. My only annoyance was that Italian drivers like to use their horn to let you know they're coming (actually, they use their horns for a lot of things, but that's another story). It's not done as an expression of hostility like here in the US, but it still gets irritating.

Get good maps (like the TCI regional maps), stay on small roads, and you should be fine.

Traffic in Florence is a bit crazy, it's very congested, the streets aren't too well marked and there are a million one way streets everywhere, but I still managed OK. The only problem is the Vespa riders, they tend to play by their own set of rules.