We've been to both Venice and Rome, although they were both city breaks. We just booked the flights and the hotels and then made our own arrangements while we were there in terms of what we saw. I can thoroughly recommend both destinations, but especially Venice - it is so beautiful. I also heard a lot of good things from (mainly American) travellers who had visited Florence as well.
As Dawn said, we had no problems with language - every time I tried to speak Italian, I got an answer in English, so in the end I gave up.
I'm sorry I can't help with any recommendations for websites or guidebooks, but have fun planning.