Pass validity is not defined in terms of destinations but in terms of participating railways companies. In Italy, Trenitalia, Trenitalia-TPER and Trenord are participating. Italo is not included.

You can travel all routes you mentioned using your pass but not on all trains. You didn't give any timetables so we can't say for sure.

Malpensa Express is not included although it is operated by Trenord. But there also other, included trains you can use. On the other hand, if Malpensa airport to Milan is the only journey on that day, it's not really worth using a travel day for.

This is amazing and kind of what I had thought with my own research. So I will ensure the train companies can accommodate our journeys which I'm hopeful they can. We are flexi on times so that's a bonus. 

I had originally priced all the travel but I think this rail pass will provide some good savings. 

And yes I think we will just use the 8 days for the main travel and not from the airport. 

Thank you so much. 

I don't count 8 travel days though:

Malpensa airport - Milan

Milan - Florence

Florence- Rome

Rome - Venice

Venice - Milan - Malpensa airport

That's 5 travel days, of which the first one could be covered by a normal ticket.

Yes I see what you mean thank you 

A return ticket for the Milan Airport - Milan “Malpensa Express” train is €20 so a pass is not worth using for a day where you are just making that trip.

For the rest of your plans listed above a 4 day in 1 month pass would suffice. This works out at approx €35/day, to this you will need to add reservation fees (€10 for the fastest “Frecce… trains) for most of those journeys.

If you are happy with pre-booking all of your trip you may well find buying them as standalone tickets directly from https://www.trenitalia.com/en.html cheaper, it will depend on dates and times obviously

I estimate in this case-a tipical newbee for IT routing, booking advance tix may work out a little cheaper-depends on how long advance, time of yr and if willing to swtich times to lower cost trains. in this case, ITalo is often a little cheaper.

Pass gives you more flexibilty to change last minute-and it may be a minor hassle, but making RES there is not that hard-@ counter or advance via oebb.at-the general fear among all newbees that one has to do that many monthes advance is complete nonsense for these trips. In IT strikes by the jolly workers are more a thing to fear!

My partner hates plans that go wrong, missed trains etc. He would also really like advanced tickets bought and in place. I'm a little different, go with the flow kinda thing (whilst also following an itinerary. Could be a disaster trip haha. 

To be clear (for your partner), it seems to make little difference whether you pre book and pay for tickets or buy a pass and simply make reservations for the same trains at a relatively small cost. Both offer the certainty of your itinerary and guaranteed seats.

However the reality (and I am speaking from experience) is that, like low cost air fares, the pre paid tickets tend to be non-refundable and non-exchange able and it only takes a small problem to miss a train, and if it is not the operator’s fault, you have no option but to buy a full price on-the day ticket.

With a pass, if you change your plans, you simply go to the local ticket office or machine for a reservation on the next express train, or jump on regional trains and catch up on your itinerary. As an example Rome to Venice on the day fare on a Freccia is 92 euro compared with a 10 euro pass reservation, if they won’t transfer your first reservation, which some operators would do.

As a convert to pass using the flexibility far outweighs the worry and lack of freedom of pre-bought tickets.

I do though enjoy the planning of my trips and, once satisfied with the timetable (e.g. booking starting and return dates) will always pre purchase reservations and hotels (usually with easy cancellation option), but with the background knowledge that I can change plans (voluntarily or forced) at minimum cost.

Incase of Italy please note that the Interrailpass needs reservations ontop of the pass in Italy (10€) 
Trenitalia offer a own pass called “Trenitaliapass” that worths a look especially with your short travel period. The Trenitaliapass can be bought for different Classes (Trenitalia have 4 of them) and includes the reservation. 

If you have a fixed plan i recommend to book cheap advance tickets of Trenitalia or Italo both companies provide High speed services in Italy.

Finally to avoid bad surprises you can try to reserve / book guranted trains of Trenitalia these trains operate even in case of Strikeactions of the Unions. (The list of these trains is a bit hidden on the italian pages of Trenitalia but you can find it)