Tough decision, last time I travelled I was still deciding the gear the night before the flight and working out what was possible given available luggage space & weight (not that I'd recommend it at the last minute). I'd go for two cameras with the same lens mount and three lenses - something like 24 or 28, 50 & 135 focal lengths - preferably with the same filter thread diameters. That way you have redundancy for both camera & lenses and one film format. Taking different systems or formats means you may need to duplicate film & lenses. I did consider taking my Lubitel 166U as a small & lightweight 6x6 option.
Film wise, I'd try to stick to one mono emulsion to save having too many of one and not enough of another. Colour print v tranny is also a tough choice, chances are if you take both you're going to have the 'wrong' one in the camera some of the time. Taking 24exp instead of 36exp might help though. I'd probably choose between HP5+ for mono, Provia for tranny and Portra 400 for print.
I haven't been to Italy with film recently, but in the UK it's impossible to get hand inspections of film at airport security, it all has to go through the X-ray machine (and if there's a 'problem' with the bag they'll often send it through again). Even removing the boxes & canisters and packing it a transparent bag and turning up early etc. cuts no ice.
John.