I was in all these places you list in Oct. 2014 and didn't know of or see any historical cards on display, and also not in Milan, which has dozens of them. They don't routinely put cards on display, because it causes them to fade. The only exhibition of historic Italian tarot cards that I know of currently is in New York, until April 17. After that, New Haven is worth trying, but phone the Beinecke Library well ahead of time to be sure. They might bring their cards out for you to look at. In Italy, as far as I know, they aren't set up for that. As it is, the only place with historic cards is the Brera Gallery in Milan; perhaps Bergamo, but it seems to me that it is now all at the Brera.
Your best bet for seeing cards in Italy is by way of their reproductions in books. Even that is not easy. Some books are hard to get outside of Italy, because the online ordering for many bookstores is often not set up for paypal or foreign credit cards. I know that is true of the Palais Royale in Milan. I couldn't order online the catalog they were selling in the gift shop. Fortunately, it appeared 6 months after the show (not tarot related) closed, on amazon.it. In relation to the tarot, many Italian books are simply out of print, which is not to say they aren't in some bookstore somewhere. As for pictures of the cards, however, most of the interesting ones are already on the Web.
What you can see in the cities you mention is tarot-related imagery in churches. For example, San Petronio Basilica in Bologna--in the dead center of the town, the Piazza Maggiore-- has the fresco of hell with hanged men and the Bolognese tarot's Devil. It is in Chapel IV, the Chapel of the Magi. Wikipedia says that it has twice been the target of terrorist attacks, since one of the hanged men is Mohammed.
Also in Bologna are the "Triumph of fame" and "triumph of death" frescoes by Costa, in the church of San Giocomo Maggiore. That church is hardly ever open, and that chapel, the Bentivoglio, is open even more rarely, but you might get lucky (I was), if there is some event going on there.
Bologna is close to Modena, which has the Da Sphaere, with many PMB-like images, all done shortly after the cards, by a different artist. It is supposedly on exhibit, one page anyway, probably under low light. There are pretty good images of it on the Web.
Ferrara has the Schifanoia Palace, which is somehow related to the tarot in various obscure ways. Be sure to go into the room at the end. It has a nice feel.
Venice is close to Padua, which has Giotto's 7 virtues and 7 vices in the Scrovegni Chapel (not part of any church); it requires timed reservations and is worth the bother. It is all beautifully restored, and you'd never guess it was done in c. 1305, as opposed to 2 centuries later.
Florence has the painting of Dante with the world of the Divine Comedy, which I find significant for the tarot. It is in the Duomo, but much easier to see on the Web.
None of these are any better in person than they are in reproduction on the Web. In fact the lighting is often worse. But perhaps there is an invisible spirit that you will somehow pick up.
Be sure to look on the Web before you go, for any special exhibitions in any of the cities you plan to go that might be tarot-related. That involves knowing what places have special exhibitions. In Florence, the Accademia, the Strozzi Palace, the Pitti Palace. In Rome: the Barberini Palace. And doubtless many more in all the places you are going.
Italy is absolutely the most exciting place in the world to visit. But then I am prejudiced. The Italians are wonderful, too. And you are going at a good time of year.