Do you enjoy local celebrations and events? You have an opportunity to see the Palio, not the famous Siena one, but a smaller and lesser known one, with all the pageantry, in Ferrara on 27 May.
https://www.ferrarainfo.com/en/ferrara/events/events-and-initiatives/folklore-and-festivals/palio-of-ferrara
https://www.paliodiferrara.it/en/
You could put Rome at the end of the trip, since you will fly out from there. Spend the night of arrival ( May 24) in Rome so you can catch the train north the following day. There are direct trains from Roma Termini to Ferrara that take less than 3 hours. You could head straight there on the 25th and spend 3 nights, enjoying the lovely city and the pre-event festivities as well as the Palio itself. Ferrara is a very nice city for walking, including a long walk on the old city walls if you like.
Then turn around and head south over the next several days, with 2 nights each in Bologna and Orvieto.
As much as I love the Dolomites, I believe they are too far north for your short time available, and Late May is quite early for the mountains. Besides, as my husband likes to say, the area is not really Italy; it is still as much Austria as it was 100+ years ago when the territory changed hands.
If you do want more time in the north I suggest Lago di Garda instead of the Dolomites. You can reach the lakeside towns with train service from either Milan or Verona.
For your arrival night in Rome, I suggest you do as we did 3 weeks ago—-book a hotel in the city in an area with something you want to see and enjoy, rather than a hotel near the airport ot the train station. Take a fixed-rate taxi from the airport straight to the hotel for €50. Book a noon-ish train to Ferrara and you will have the morning for walking and shaking off jet lag. We chose a hotel just blocks away from the Birghese, and could have visited the Villa itself in the morning, had we not seen it before. Instead, we chose to walk around and enjoy the park. The taxi to the train station took less than 10 minutes and cost very little.
In Ferrara, I highly recommend Hotel Annunziata, just across a pretty car-free square from the Castello Estense. It is a small, family-run hotel offering a warm welcome, nice rooms, and one of the nicest breakfasts we have seen. The family went above and beyond to help my by retrieving my little tote bag from the nearby restaurant where I inadvertently left it the night before, even though the restaurant was closed all the next day. They knew the owners, and Zeno arranged to have his mother meet someone at the restaurant to unlock the door and find the bag. It was back in our room when we returned from our morning walk.
https://www.annunziata.it/en/
https://www.ferraraterraeacqua.it/en/ferrara/discover-the-area/art-and-culture/castles-towers-bell-towers/estense-castle
I am surprised to see they still have rooms available during that event, but I wouldn’t wait long to book.
