Raphillon, if you're still in a generous mood, I might try to contact you when I'm ready to head to Rome in October! We're coming from stateside, so I'll probably be coming into Fiumincino, and we never pack much of anything except one 22" rolling bag and a backpack.
Of course, I'm only there for 3 weeks.
Of course, inside that rolling suitcase is another suitcase for all the tons of ridiculous things I can't live without!!
Weather-wise, I was telling someone recently that I have been always always always told--in 9 trips to Italy-- that the weather was: warmer, colder, rainier, foggier, colder, drier than it ever had been before!
Pack for layers (as someone who lives in SF and has to go from 50-80 degrees (f) everyday, and think zip out lining coat, one serious sweater and silk long underwear (it breeeaaathes!). You can find it fairly inexpensively online at the Sierra outlet! And don't forget that umbrella!