12 Day Itinerary in Italy - with a 3 day wedding in Cannes

I assume you are flying in and out of Milan, although that is not what I would have done. I would have flown to Nice and returned from your last stop in Italy. Your plan is too ambitious. Italy is bigger than it looks on a map. For planning count nights, not days. Basically 2 nights in a location are one full day at that location. Try to stay at least two nights at one hotel. changing hotels too often its time consuming. it is more efficient to visit places doing day trips from a central location. Look at a map to decide the itinerary. A car is not necessary, and actually it's a hassle to have while in big cities (Rome, Venice, Florence) and also at the Cinque Terre. Cinque Terre needs at least 2 nights (one full day) Florence 2 nights minimum Tuscany 2 nights minimum You could also stay 4 nights in the same place in Tuscany and visit Florence from that location. Florence is the capital of Tuscany. If you have a car,staying in Florence is not a good idea, because of traffic restrictions) Rome 3 nights minimum Venice 2 nights minimum Amalfi Coast 2 nights minimum
If you fly out of Milan, you need one last night there. I have listed 14 nights already, therefore you might have to cut Amalfi coast or something else out. Italian food has plenty of vegetarian options. Have a good time planning.

Cont'd Since a car is not necessary in cities, you could drive to Cinque Terre, then Tuscany, then return the car as you enter Florence. You could then visit Florence and travel to Rome and Venice and eventually Milan by train. A car in those cities would be gathering dust in a garage, because you cannot drive in them.

Vegetarian is easy in Italy... lots of good salads, pastas, pizza. It's a little more challenging if you also don't eat dairy, but still easily doable. I wouldn't want to cover the territory you're describing in either 9 or 12 days, but I think our travel styles are very different.

"my wife and I often like to see as much as possible, with some quality time in each" With only 12 days, and with 3 days committed to the wedding, you will have to choose which is your priority for the rest of the time. You can have a blitz tour of the places you listed (think of The Amazing Race), or you can choose one-half to one-third of them and have the quality time. But the places you listed are just too many, and far apart, to do both. To get estimated driving times, you can use http://www.viamichelin.com, but note that many say their times are very optimistic. And remember that due to ZTL's, you will have to allow time to park outside of cities and then get into them by bus. Speaking of which, be sure you know about ZTL's and the International Drivers Permit, to avoid nasty and expensive problems. Furthermore, Italy is not geared for a busy touring schedule. For instance, in many places, lunch is served from 1 to 3 and dinner from 8 to 11; it can be very hard to get a sit-down meal outside those hours. And restaurants only have one seating, because once you have a table, it's yours for the whole afternoon or evening; if you show up at 2 PM and all the tables are taken, you won't eat lunch at that restaurant. If you're thinking, "that's OK-we'll just go to a grocery and buy something," be aware that many small groceries are closed from 1 to 4, and larger supermarkets are very scarce in the centers of cities. You can always go to a bar (the Italian name for what we would call a cafe), but you may not like the food on offer (it's mainly a place to get coffee, sodas, wine, and other beverages). All this means that sightseeing and travel in Italy must be planned around mealtimes much more than you may be used to. You can't just show up in town at any time and get fed, like in the US.