Count nights in each place when you plan your trip. Two nights in a place equal one full day, three nights are two full days and so on. Travel days from hotel to hotel are largely wasted days on the transfer (pack, check out, travel, check in, unpack), therefore I like to stay at least two nights in each location because changing hotels is a time waste. Sometimes it's more efficient to visit places on day trips from a central location, rather than hopping from hotel to hotel in different cities.
My minimum night stay recommendation in your locations:
Paris: 5 nights
Chamonix: 2 nights
Milan: I never cared for Milan, but if you want to go, give the min 2 nights
Lake Como: 3 nights
Venice: 3 nights
Florence: 3 nights for Florence only, 4 nights, with one day trip to Siena. If you want to take more day trips within TUSCANY add as many nights to Florence for each day trip.
Cinque Terre: 2 nights
Naples: 2 nights, 3 if taking day trip to Pompeii from there.
Amalfi coast: 3 nights with day trip to Capri. Note that some people prefer to use Sorrento as a base and take day trips from Sorrento to Capri, Pompeii, Amalfi Coast, Naples, Ischia, Procida, etc. it depends if you like large cities or smaller size resort towns.
Rome: 4 nights.
As I said these are just MY minimum stays suggestions. Add more to where you have more interest and decrease (or skip) where you have less.
Do the itinerary in the exact order I listed it.
Buy an open jaw airplane ticket with arrival to Paris CDG and return home from Rome FCO.
