Italy and Switzerland

There is bus service from Bolzano to the Dolomites. You may find that you don’t really need a car. It depends on where exactly you want to go in the Dolomites. You could base in Ortesei and take the cable cars to Seceda & Alpe di Siusi. Then take the bus to other villages in the area. Your hotel will give you a free bus pass that covers Ortesei, Santa Cristina and Selva. https://www.val-gardena.com/en/summer/mobility/

Since you're going to be in the Dolomites, have you considered renting a car and going north into Austria's Tirol? It's the same mountains as Switzerland but we find Austria less expensive and easier to travel through.

The mountains northeast of Cortina and north of Lienz (Austria) are the prettiest place we've ever been. There are other great cities like Salzburg and Innsbruck that are in close proximity.

Mid-May to Mid-June is not optimal for the Dolomites if you are planning on hiking. You can refer to this season’s schedule here to help you plan if you are interested in the Val Gardena. With 4 weeks for your itinerary I suspect you’d land wherever you decide to stay by about June 1, so bear in mind which lifts are open and when are not in your planning and look up the same for other valleys if that is your intent. You specifically mention Bolzano but that is not “in” the mountains. It is about an hour from Ortisei in the Val Gardena by bus.

The Val Gardena is highly accessible by public transportation if that is what you prefer. Once you are there, your car will remain parked a great deal of the time if you take advantage of the free bus pass handed out by the hotels.

If your plan is to go deeper into the Dolomites like the Val di Fassa or Cortina or Val Badia, a car might make sense as public transportation fro Bolzano will take a lot longer.

As to Switzerland in June, I think you will also find some snow up high, and mud, but depending on exactly where you want to go and what you want to do, trains and lifts run all the time with the exception of some seasonal shutdowns for maintenance. Which airport you fly home from depends on your route. Which trains do you want to take? The scenic ones like the Glacier Express, Bernina Express, Golden Pass, and Gotthard Panorama Express? Rick Steves covers these extensively in his Switzerland guide book. Do you have it?

As travel4fun mentioned, you can take the buses in the Dolomites if you don’t want to rent a car. We also did that when we went back to that area and stayed in Moena in the Val di Fassa area, south of Ortesei. We took the train up from Verona and bus from Trento.

What are you planning to do in Bologna? Verona might be a good substitute. And see if you’d rather stay in Bergamo up in the Citta Alta old center instead of Milan.

I also really like Nice & area where you could spend several days. It probably just depends on how much time it takes overall by transportation for that route.

If it is a good snow year, the hiking in the Dolomites may still be very wet and muddy even into mid-June.

I agree it is doable by bus, but I agree it is best seen by car if you are planning on more than one specific area. We based out of Ortisei for five days and the car never left the garage so we could have taken a bus. However, if we wanted to add a couple other towns, the car would have made even more sense.

I would strongly advise adding Lucca into the trip planning on the way to/from CT. I could spend at least three days there and the weather is perfect at that time of year as I understand. Also, if you like wine, the Piedmont region is outstanding as well.

From Bolzano you can take the train to the Dolomites too, via the lovely and nicely touristy Pustertal valley. The Dolomites are a big range; you don't need to go to the most famous tourist areas to see amazing mountains and pretty alpine villages.

Also! From Bolzano you can use the train and then very nice Swiss Post Bus to quickly travel to some painfully gorgeous parts of Switzerland. You have picked a wonderful area to explore - would be tough to go wrong no matter what you decide to see and do👍