Hi Tammy—-Bologna is an excellent choice. We have been there twice, for 5 days each time, and keep discovering new things to see and do. You might consider taking a night from Florence (which is extremely crowded these days) and adding it to Bologna. Our list of top things to see and do there:
A daytrip to Ravenna to see the stunning mosaics.
Climb the Clock Tower to see the mechanical workings of the clock, and go outside on the terrace for a view over Piazza Maggiore and the famous Neptune statue:
https://www.bolognawelcome.com/en/places/towers-historic-buildings/torre-accursi-o-dellorologio-2
And be sure to go inside the Basilica de San Petronio. This church is remarkable not so much for its art, but for the Gothic architecture spanning such a huge space, and most of all for the meridian line on the basilica floor:
https://pauls-bologna.blog/2017/11/02/the-meridian-line-of-san-petronio/
This feature is unusual in a church of that era, due to its importance in the realm of science. It helped confirm Galileo’s heretical idea that the earth rotates around the sun, not vice versa.
For Venice, be sure to book a free visit to the rooftop terrace at the upscale department store Fondaco de Tedeschi. The store is worth a visit for the architecture as well, and you can marvel at all the Gucci and Prada so beautifully displayed. The food section in the basement is pretty amazing as well. It is a great way to escape the Venice crowds. They limit the visit to the terrace to 48 people for 15 minutes, so it is not crowded either. Reservations open up exactly 21 days in advance. Send me a PM about a month ahead of your visit and I can explain exactly how to score the reservation—-it is highly competitive!