I do all my own planning and booking. I have received an amazing amount of help from this forum over the years. I was hesitant to do it all myself for the first trip but it ended up being quite easy- with help from here, Google and RS Italy guide book and others
If you don’t already have it- do get the RS Italy book. I like the Kindle versions better now- easier on my aging eyes!
He has excellent practical info (in particlar on how to get to and from).
I gave you less time in Florence because you said you were not that into museums, Florence is all about the art. There are plenty of other things to see/do there and you could pick just a few lesser museums if you don’t care to spend a lot of time in the Ufizzi for example. We love the Bargello museum and San Marco museum. And you must see the David. Basilica of Santa Croce is super interesting.
Climb the Duomo.
Mercato Centrale is great- have a few meals there.
For “Tuscany”- it is easy to go to Siena on your own to spend the day but if you want more there are guided bus tours that get good reviews- will take you to a few hill towns- and maybe lunch at a winery. The hill towns are difficult to visit without a car.
Walk of Italy has one, there are others.
Siena is definitely worth a night or 2- and if you really wanted you could stay there 3 nights and day trip to Florence.
We love Florence but were there this past May and oh my gosh was it CROWDED!
Sorrento- you need the 4 nights there- mainly because coming from Florence it will take the better part of the day to get there, leaving you only 3 full days.
1 day for Pompeii
1 day for Capri
1 day for Amalfi Coast towns
Spend your evenings in lovely Sorrento.
Sorrento might be a good place to take a cooking class.
We spent our 40th Anniversary there and splurged a bit on our hotel. It was fabulous.
Grand Hotel de la Ville
https://www.delavillesorrento.com/
This area books up completely so you will want to make your decision and book something soon.
Capri- we did the boat trip with Mondo Guides
www.sharedtours.com
It was one of the best days we’ve ever had while traveling. Skip the Blue Grotto- it’s a tourist trap and time suck. The boat trip around the island was actually the highlight of the day for us. The crew was so fun and knowledgeable.
Mondo Guides also offers very affordable day trips to AC towns.
Other things we have enjoyed-
Venice
Get a length of stay vaporetto pass.
Visit the lagoon islands- our favorites are Burano and Torcello
Go across to top of San Giorgio Maggiore for amazing views.
Secret Itineraries Tour of Doges
https://palazzoducale.visitmuve.it/en/pianifica-la-tua-visita/special-itineraries/secret-itineraries-tour/
Alessandro’s Cicchetti tour
https://www.schezzini.it/
Rome
Forgot to mention the Capuchin Crypt- really interesting- if a bit creepy. Not a huge tourist draw either
https://museoecriptacappuccini.it/
I use booking.com - you can trust the reviews there as they can only be left by the who have actually stayed at the property.
Use the filters to narrow down your searches.
You will need Air Conditioning!
Once you are firm about your itinerary- come back and seek help on transportation.
Trenitalia (fast and regional) and Italotreno (fast) are the 2 train companies. Both have easy to use apps.
https://www.trenitalia.com/content/tcom/en.html
https://www.italotreno.it/en
All of your train routes offer fast trains. (From Naples to Sorrento is a local train- Circumvesuviana)
You might want to get familiar with those sites now.
Do some dummy searches to get an idea how it works, cost of train tix, etc - be sure you are using the Italian names for stations
Venezia S Lucia
Firenze SM Novella
Roma Termini
Napoli Centrale
Enjoy the planning! I like that bit as much as the actual travel.
Don’t be afraid to ask questions about anything- lodging, tours, etc.
You’ve got a wealth of free information and help here.