90 day trip to Italy in 2 years.

Probably will not like this response but just in case there is a slight misunderstanding of the Schengen zone rules, I would only plan a trip of 85 days just to give a little wiggle room in case of an unexpected delay. You broad outline looks good. Covering a fair amount of ground but at a reasonable pace and it can always be adjusted. Our preferred time for that area is Sep/Oct. A little cooler with less potential for rain. I don't see any problem moving north to south. Keep in mind the days will be getting shorter. September to mid Nov. returning middle of third week, would be my preference.

Are you planning to use public transportation, a rental car, or a mixture? Before committing to a one-month rental period anywhere, I'd like to have a fairly decent idea of what places I wanted to see on day-trips so I could check travel times. I do a lot of day-tripping via public transportation myself, but I don't do it by spending as long as a month in one place. I stay 10 - 14 days in large cities, primarily to see the sights in those cities, and shorter periods in smaller towns for access to surrounding places of interest. For me, that strategy has two advantages: I spend less time making out-and-back trips along the same rail lines and roads, and I don't pay big-city lodging rates for a bunch of days when I'm sightseeing in smaller towns, where costs are often significantly lower.

I'm wondering whether one month in Florence will be a practical way to see all that you want to see in Tuscany. I'm not sure about the Amalfi Coast, either. I have a vague impression transportation in that area is fairly slow.

I second the suggestion that you not push your trip to the absolute 90-day limit. On my first trip to the Schengen Zone I got sick around Day 85 and just barely escaped over the Slovenian/Croatian border in time.

Congratulations on your upcoming retirement! And this trip to Italy sounds, to me, like the perfect way to celebrate it!!!! But then again, most of us don't need an excuse when it comes to Italy. :)

With your proposed schedule I think you'll experience a variety of weather conditions. Either pack for heat/humidity, cool nights, and rain or enjoy some shopping. I don't know why people fly into Milan. I never found it convenient. I prefer Venice, but that's a personal choice. 30 days in Florence allows you plenty of opportunities to enjoy the city, the art, the shopping and the food. It also makes places like Siena and Lucca a fairly easy day trip. Check out the train and bus schedules - there are plenty of other places that can be nice breaks. May I suggest looking at Sorrento as a home base? Transportation to Pompeii, Amalfi Coast, Capri, Naples is frequent and easy. I love ending my annual trip to Italy in Rome for at least a couple of weeks. Flying home from there is getting easier. One of the nice things about Rome is that again you have plenty of great choices for day trips. And, if you get tired of one century, all you have to do is turn the corner - there are more than 2000 years of history and culture to explore! Most of all, remember: You deserve this!!!!!

To celebrate my retirement, we went to Italy for 6 weeks. We rented a cottage for 2 of those weeks, in a hamlet close to Castiglione del Lago, which is in Umbria, almost at the border of Tuscany.
I highly recommend the location. We were minutes from the A1, which gave us access to many Tuscan towns,e.g., Arezzo, Cortona, Montalcino, and Montepulciano. In Umbria, we visited Perugia, Deruta, Assisi, Gubbio, Spoleto, Spello, Montefalco, Bevagna, and Urbino.
Two weeks, or perhaps 18 days, would be good time allotment for that region. Renting a car made it all possible. I wouldn’t try to get around there without a car.

You can also fly non-stop on United between Naples and Newark so you wouldn't have to backtrack back to Rome. Since you're going to Camogli, flying into Milan is probably your best bet. Milan flights are usually cheaper than flying in and out of Rome. If you want to include the Dolomites, I would fly into Milan or Venice and go there first, then to Camogli before going to Tuscany.
I was in Tuscany in Nov and thought it was a wonderful time to be there except for the fog in the morning making visibility an issue when trying to enjoy the view as I was traveling along one of Tuscany's scenic roads. But don't let that stop you from going that time of year because the temperature made sightseeing comfortable.

I’ve spent a week in Florence in November 2018 and again in 2019. Great, and uncrowded time to be there, although I didn’t venture into other parts of Tuscany.

Had some rain, and one day it was absolutely pouring. Had the Brancacci Chapel all to myself for admiring the astonishing artwork, and for calm contemplation. Cool temperatures, but quite pleasant those other days, when it wasn’t raining. Outdoor dining wasn’t an option, but it overall was so good the first time, I returned again the following year!

Thanks for all the responses. I will probably keep my time closer to 80 days than 90. I tagged Camolgi on because my Father's parents came from there and I thought It would be fun but not very convenient. Kind of like the Dolomites. I really don't want to pack and unpack a lot and may just stay south. Acravan I am not excited about renting a car but maybe If I stay in Tuscany/Umbria area and drive around there for 2 weeks and Florence for 2 weeks? That does seem like a lot less time on a train from Florence.
When would be the best time for the Amalfi coast? Maybe start there in sept when the weather is warmer. Then Florence/Tuscany. I want to end in Rome in Oct/Nov. Does anyone know if Christmas decorations have started in Rome in November? Since the days will be shorter then I want to stay close to nighttime activity as well. So much to think about and I have plenty of time. It may all boil down to cost.

Your plan sounds good.
The weather (in Florence at least) is amazingly similar to the weather in Durham. Except that Italy is drier in August and September (but wetter in late October/early November). Temperature wise it’s the same as Durham.

Since RDU airport has non stop flights to London (with American Airlines) you might want to consider flying to Italy via London. The UK is outside the Schengen zone, therefore as long as you are in London within 90 days you are safe from any immigration violations. Also London is a beautifull city that is worth a long 3-4 day layover.

If you get to Italy in the second half of August, the weather is going to be hot, at least till the early part of September. If you don’t like hot, Florence (my native city) is not the place you want to be in August. Coastal towns (like Camogli) are a better choice thanks to the sea breeze. Dolomites mountains would be a good choice too. The Amalfi coast has great weather as well, at least through most of October. End of October and November is traditionally very rainy and in November it starts to get cold, therefore I would avoid coastal towns or Dolomites at that time.

End of October and November is when you should consider cities like Florence and Rome (Rome has a little better weather than Florence in November). Florence is also good for day trips to many Tuscan towns.

If you are in Florence in early November please be aware that Florence has had 3 destructive great floods in its recent history:
On November 3, 1844
On November 2, 1944
On November 4, 1966
The most catastrophic in Florence history was however in the year 1333. Also on November 4.
Please don’t rent an an apartment on the ground floor, and make sure you buy a strurdy umbrella if you plan to be in Florence the first week of November. That week is cursed, particularly when the last two digits of the year are the same number, in case you are traveling in 2022.

For a long holiday in Italy probably the best period is Spring. I mean From April to June. The weather and temperatures are not so different than Fall, but the daylight is longer. So more time to stay outdoor.
In general both Fall and Spring are good periods to travel in Italy: the first for foliage, the second for flowers blooming. Both in Spring and Fall is plenty of festivals everywhere, so when you have a program check in the area and you find someone.
About distances Italy isn't USA: everything is not so far. From Florence to Trento for example is a 3 hours and half route driving: you can do it in one leg without stop, if you like to drive (or 2 hours and half with a direct train). So you can create the itinerary you prefer without being to much worried about distances.