Help with 9 day Itinerary - Italy

The conventional meaning of "night train" is a train that takes all night long to get you where you want to go. I think you probably know that there is express-train service between Naples and Rome and between Florence and Venice that will deliver you to the new city very rapidly. You can check rail schedules on the user-friendly Deutsche Bahn website to see what options you have for evening departures.

You'll need to go elsewhere when it's time to buy your tickets. Do not use RailEurope.

Your time would be best served skipping Naples and the Amalfi Coast. You are right to realize the first day and last day of any trip is wasted. And every time you moved, it's a wasted day.
You should start in Rome for 4 days plus the day you arrive. If looking for a day trip from Rome, I suggest Orvieto which is a great hilltown just 70 minutes north by local train.
Then take the train to Florence and spend 3 days. A day trip down to Siena would be better time spent (1 hour by bus) than Pisa.
Spend the balance of your time in Venice.
These cities are so important in architecture, art, food, culture and history that they deserve to be visited slowly.

I would also skip Pisa. Field of Miracles is only worth an hour or two. Very crowded, overrated. Stay and see Florence and see those sights. Or, if you want a trip to experience another town, try Lucca.

Day 3 Naples / Day trip to Positano and Pompeii (tour group or driver, is this possible in a day

I suggest you 'pick 1'

Also you may want to peruse the "Itinerary" tab of this tour to get an idea of how ambitious your plans are to go 4 places in the same time span.--- https://www.ricksteves.com/tours/italy/venice-florence-rome

Night Train to Venice

Its a bit over 2 hrs to train between these cities

Yes, sorry i did just mean catching a train at night that was all.
Okay so it seems i have to make a decision to drop Naples or Florence.
I really wanted to see Capri, the Amalfi Coast line and Pompeii. Now my husband he wants to see the Leaning Tower and that was about all we had planned on doing in Pisa with basing ourselves in Florence and doing a day tour to Leaning Tower of Pisa. With everyone's advice i might just drop Florence and add a day to Naples and add the other day to Venice or Rome... Grr its so hard to decide and specially when you have limited holidays and want to fit in everything, I am coming all the way from Australia. I wish i could just do it backbackers style and leave for a few months!! Thank you all for your ideas. I will revised my plan

I have added a day to Florence and looked into Tours to Pompeii and Positano so dropping Naples seems silly if that is where we fly into. How about this?

Day 1 Arrive Naples in Afternoon / Check in Hotel / Do nothing / Jetlaged
Day 2 Day trip to Capri
Day 3 Day trip to Positano and Pompeii (tour group or driver, is this possible in a day????, i have seen tours that leave Rome that do this trip in a day, so i believe its do-able from Naples surely? ) - Leave for Rome at night by train (hotel near Train station)
Day 4 Full Day Rome
Day 5 Full Day Rome
Day 6 Full Day Rome
Day 7 Early morning Train to Florence Check in Hotel have afternoon/ do nothing
Day 8 Florence - I want to see the Statue of David that is about all
Day 9 Day trip with driver or tour to Pisa (to see Leaning Tower) or Lucca (Maybe i should just go Pisa to stay and not Florence, then leave from Pisa to Venice?- still confused about this part and think i will just drop Florence all together) Night Train to Venice arrive Venice check in hotel and do nothing for the evening.
Day 10 Full day Venice
Day 11 Morning Venice do nothing - Night Flight to Paris.

I am then doing 5 nights in Paris and 3 nights Barcelona flying home from there
Nearly a full 3 weeks travel.

First off, I'd reverse the order. Start in Venice, end in Naples. Venice is the perfect place to get over jetlag - you can soak in the atmosphere and adjust to the currency, language, etc., in this slow-paced, quiet, highly walkable city. Naples is probably the worst place to be introduced to Italy.

You can easily go to Pisa and Lucca on a day trip from Florence by train. You don't need a tour or a driver. It's better to stay in Florence because of the train to Rome.

So, just to be clear, it seems your flights are non-negotiable.
Let's face it, we all have reasons we want to go to a country. If Capri and Pisa are heart set, then let's try to make that happen. You will kick yourself if you let yourself get talked out of it.
Tours make the activities fit the hours. Sure you can do a Positano and Pompeii trip in a day. Whether it gives either place as much time as you would want if you did it as a DIY, well, that is the decision maker.

As far as Pisa, sure it can be busy, but see what might interest you besides the Leaning Tower. There are numerous leaning towers in Pisa, by the way. Chances are you will pass them enroute from the train station.
I have fond memories of a great gelato stand enroute as well. 4 flavours = dinner.
I will admit we didn't actually climb the leaning tower. My travel mate's knees wouldn't allow it. Instead, I climbed the Baptistrynext door to get one of those iconic Leaning Tower photographs out of a window. I also enjoyed being in the dome, as it is a double dome like St. Peters, where the workers often lived while working. Let your imagination go wild what that might have been like. Also - the icing on the cake - was the a cappela singer showing off the acoustics of the Baptistry. You can see/hear it on YouTube, but in person, it sent shivers up my spine and tears to my eyes - it was so beautiful. Those are my memories of Pisa; maybe you want to add them to your plan. Oh, and said, from Florence you don't need a driver, but maybe a guide would bring the city more to life for you than the 'overrated' comments infer.

How late do you expect to leave Pisa?

Trenitalia says that the trip to Venice is about 4 hours. Perfect for a train picnic - IMO.

Note: Even though the site is in English you still need to use the Italian station names ("Pisa Centrale", "Venezia S. Lucia" (NOT "Venezia Mestre", don't get off at Venezia Mestre, don't stay in Venezia Mestre))

I think you can do everything by changing your path slightly.

Day 1. Arrive Naples.

Day. 2 Capri.

Day 3. Pompeii, Sorrento and Positano
https://www.sharedtours.com Good company much better than the big bus tours.
Evening train to Rome.

Day 4. Rome.
Make sure you book the sites you wish to visit before you arrive.

Day 5. Rome.

Day 6. Rome.

Day 7. Roma Termini-Pisa Centrale.
Early trains @ 6:05-8:26 2H21m. #8602
Next train. @ 6:57-9:53. 2H56m. #8606.

Check your luggage at Deposito Bagagli
€5 p/bag.

Take the Lam Rossi bus to Campo dei Miracoli.

When done, return to Pisa Centrale train to Firenze SMN. 1 hour.

Day 8. Florence. David at Accademia.

Day 9. Florence. Some great sites here to see.
https://www.florence-museum.com

Day 10. Train Firenze SMN-Venezia S Lucia.
2H05m.

Purchase a 24 hour Vaporetto pass. €20. Unlimited rides. Individual tickets €7,50.

Great fun free tour. http://www.venicefreetours.com

To visit St. Mark's Basilica and skip the line use.
https://www.venetoinside.com/attraction-tickets-in-veneto/tickets/skip-the-line-saint-marks-basilica/

Try to go around 11:30 to see the Moasics lit.
The museum located upstairs €5 is worth it.

Day 11. Venice. Evening flight.

Edited to add links.

gerri, thank you so much much appreciated for your time and effort. You are amazing :)