18 night itinerary suggestions

Not certain how you are planning Pompei and Naples as a day trip from Rome...is it a tour? We stayed in Sorrento for 3 nights and did a day trip to Pompeii from there as well as a day trip to Capri . Alternatively you could stay in Naples and do day trips to the Amalfi Voast , Pompeii and Capri from thete.Naples does not get much love here on the Forum with some exceptions but we enjoyed our stay very much.

People will probably tell you not to do a day trip to Pompeii and Naples, that it's not worth it, your travel time is long and your time in Pompeii will be short, etc., but my husband and I did a day trip to Pompeii and Sorrento, and we thought it was great. Did we see every single thing in Pompeii? No. Pompeii is huge. But we're pleased with what we did see and probably wouldn't have wanted to spend too many hours more there, anyhow.

We went to Florence and Venice and a couple of other places that are different from your itinerary, but I think it looks pretty good, except for maybe the Milan bit, which really gives you only 1 full day. If it were me, I'd probably spend 2 more nights in Rome, instead, because 4 nights gives you only 3 days there, and one of those will be your day trip, so that leaves only 2 days for Rome.

But that's me. If Milan is important to you, then disregard.

You are planning to book open jaw flights (aka multi-city flights), right? That is, you'll fly into one city and out of another, which saves you from spending time backtracking.

Hello-welcome to the forum!

18 nights is a great amount of time and Sept/October good choice as well.

Can you tell us a bit more? Have you been to Italy before, traveled abroad before?
Where are you flying from? Have you searched flight options?
Will you travel by train in Italy?
What are your interests? History, art, food, nature, nightlife?

4 nights in rome (pompeii and naples day trip)

Good- Rome deserves at least 4 nights

There is no need to take a day trip to Naples/Pompeii (hard to do both in one day) if you are going south to Amalfi anyway.

3 nights in Positano (capri day trip)

Not necessarily best town to stay in. Transportation is an issue as is all of AC, ferry service to Positano is iffy. Make sure you have that bit figured out.
We thought Positano was worth just a few hours.
Getting from Positano to Florence will be an all day trip with a couple of changes.

Sorrento is a better location for visiting Pompeii, Capri, Naples. Not ON the AC but transportation hub, fun town, good food, nice views.
Transportation on the AC/Sorrento area is chaotic, crowded and can be expensive.
For your stay on the AC-visit Positano, Amalfi, Ravello, Minori, Vietri, etc. Stay anywhere with good ferry access.

3 nights in Florence (pisa/wine tour)
- 3 nights in Venice
- 3 nights in Lake Como

Good amount of time in these locations.
I like that you have mostly 3 night stays- well paced

2 nights in Milan

What is your interest in Milan- or is this just for flight out?

All great places to visit but also all very popular and still crowded in the fall.
You might consider dropping one of the big cities/very popular places and adding a small town stay for a break from the crowds. Not sure where that would be.

Try to fly multi city- in to Venice out of Naples would be my preference. Or in to Venice, out of Rome. Easier to fly in to Venice, than out of.

First trip- I would choose the 3- V, F, R and either Lake Como/Milan or Naples/Amalfi. You are trying to cover a lot of ground.
You have lots of things listed to do in AC area, with 18 nights you have the time to give that area what it deserves.

Make your transportation as simple/direct as you can.

Venice 3 perfect place to get over jet lag
Florence 2 plus 1 night for every day trip (Siena, Pisa, Tuscany wine tour)
Rome 4
(Train to Salerno-driver or ferry to AC town)
Positano/AC 3- visit Ravello, ferry along coast
Sorrento 3 or 4 - vist Pompeii, Capri
Naples 1 or 2
Fly home

You must be in your departure city night before flight so if flying home from Rome-

Venice 3
Florence 2 plus 1 night for every day trip (Siena, Pisa, Tuscany wine tour)
Positano/AC 3
Sorrento 4 - vist Pompeii, Capri, Naples
Rome 4
Fly home

Do you need any links to trains, sights, lodging?

I only can help about Lake Como:
The most beautiful area there is the eastern coast, Varenna. From there you have the best connection around the lake by ferry, and on the whole eastern side by train.
But to go from Venice to Lake Como is a bit difficult and takes at least 5 - 6 hours. You have to go by train to Milan Centrale and another train from there via Lecco to Varenna (or any other town).

You need WAY more time in Rome.
I have been to Rome twice spending 10 days there and still not seen it all.
Suggest at least 5 days in Rome with NO day trips.
Do Pompeii and the Naples area needs 3-4 days to see Sorrento, Capri and the Amalfi Coast. You indicated 3 nights in Positano, so do Pompeii when you stay in Positano.

Milan's cathedral is great, but Rome still needs more time.