trip to Italy

Bologna is a good base for day trips by train (Ferrara, Modena, Padua are just a few) plus at least a day seeing the city itself. You could even day trips to Ravenna, though I'd stay a night or two. Verona can be a day trip from Venice, but if you are going to Lake Como and Venice, it's also worth an overnight between them. Have you been to any of the towns before? If not, I'd say at least 1.5-2 days net in Verona and Ravenna, 3 in Venice. I haven't been to the others you mention. I'd use Pisa as a base to visit towns in Tuscany, maybe the CT (depending on cruise ship schedules). Arranging the itinerary depends on your airport/s and whether you want to both begin and end in Pisa. Sounds like the start of a fabulous trip.

Thank you for your ideas! We're really excited about this trip.

Haven't been to San Marino.

I am not sure if you are asking how to arrange your stops as daytrips from Pisa, or if you want a second (or even third) base city for a couple of nights each so you can daytrip from there (Bolzano, for example, should probably be at least an overnight).

Bologna is a good base for daytrips, if you have a couple of nights to spare; Parma, Modena, Verona, Ferrara, Ravenna, Mantova can all be reached from there, but each of these cities deserves a day. I would stay overnight in Ravenna and perhaps Ferrara as well.

If you have a couple of other nights away from your base, I would suggest the Colli Euganei in the north, or go south to Southern Tuscany (Montalcino, perhaps, with daytrips around there).

So if you plan to be in Pisa most of the time, your northern Tuscan daytrips (Lucca, Pistoia, Volterra) can be done from there.
Bergamo can be a daytrip from Lake Como (depending on which town you are in).

Most of our time will be spent away from Pisa, although we will be taking a few day trips from there. With the exception of a few hours in Venice, we have not been to any of the towns I listed, and they are top priority. Thanks for your suggestions.

Bologna would be the best base for most of them. From BO you could visit easily Bologna, Parma, San Marino (train to Rimini then bus to RSM), Ravenna, Verona for sure. Venice is also very close and easily doable as a day trip from Bologna, just a bit over an hour by train, although you might want to spend more than just a day trip in Venice, it's up to you. Lake Como, Bolzano, and even Bergamo would be challenging to visit from Bologna, since they are farther. You can but you'd be left with very little time to actually visit those places.

From Pisa it would be a challenge to visit all of them in a day, except for maybe Bologna and maybe Parma. Bologna is relatively close (about 2 hours via Florence), Parma can be reached in just over 3 hours from Pisa via Pontremoli, but all other places you mentioned would need several hours to reach from Pisa, therefore would not be easily doable as a day trip from there.

Pisa is our home base, but we are planning to spend at least 14 nights away from there---relatives live there now, so we can return and do laundry as needed. I appreciate the suggestions, and was thinking of 2 nights at most of the places I mentioned, except for San Marino (day trip only). Everything is still in the planning stages now, and the more information I get the better.

I stayed in a budget hotel, about 1/2 way between the historic center and the train station (10 minutes on foot each way). Very convenient for day trips and lots of dining options when you get back if you haven't eaten yet.

Bologna - 3 nights (excursion to Parma)
Ravenna - 2 nights (excursion to San Marino)
Venice - 3 nights
Verona - 3 nights (excursion to Bolzano)
Bergamo - 1 night
Lake Como - 2 nights

If you are in Pisa, why not visit San Gimignano, Cortona, Sienna, Lucca, Pistoia, Vinci, Peruggia, Gubbio, Arezzo,
Isola d'Elba. Do you really like to travel plenty of miles when you have so many things you could do nearby.

Genova and La Spezia are also worth a visit if going to the CT