Itinerary 45 (ish) days in Eastern (Central?) Europe

Prague 6 nights is a bit much, cut to 4
Triste 3 nights, consider eliminating. I visited that city and was underwhelmed.

Consider adding Ravenna (one day is enough)
Consider adding Warsaw

Are you traveling by train once you're on the ground in Europe? If so, you have a long way from Dresden to Krakow and then back to Prague. Maybe consider moving Krakow between Bratislava and Budapest. Or reorder it to Berlin - Dresden - Prague - Vienna - Bratislava - Krakow - Budapest. Whatever you do, Krakow is going to be a bit of a detour, but I think you can order it so it's not such a long train ride in both directions.

I would add a day in Berlin. Four days is not really enough, especially if you are likely to suffer from jet lag on your first couple of days.

I would also add time in Dresden. In addition to seeing that beautiful city, I think there are two excellent day trips: one to Leipzig, and one to Saxon Switzerland.

Since you mention cemeteries, don't miss Vyšehrad Cemetery in Prague and Žale Cemetery in Ljubljana.

Overall, it's a great trip during the best time of the year to travel, but it features a lot of mid-size and major cities. I have a couple ideas on small to mid-range towns with a lot to offer in terms of culture, history and activities.

Because you'll be in Hungary, I would suggest two towns: Pecs (pop. 150,000) and Eger (55,000). Both offer a chance to slow down in tows with a lot of culture and activities. Eger is north of Budapest about 75 miles, and Pecs is south of Budapest about 125 miles.

You'll be in Croatia. A stop in Rovinj on the Adriatic Sea will make you fall in love with the country.

You'll also be in Slovenia. Visit Lake Bled in the Julian Alps. Its surrounded by mountains.

In Germany, my favorite "small" town is Bamberg, which is about 2 to 3 hours south of Berlin in the northern part of Bavaria state. It's also beautiful and interesting.

In-mail if you want specific details on things to do in any of these.

Hi, I think you may be doing southern Poland a bit of a disservice, you're missing out on a lot of cool things along the way.

First I would take out 1 night each from Prague, Budapest, and Zagreb. Then add 1 night to Krakow, especially if you plan to do daytrips to either Auschwitz or the Tatra Mountains. Krakow is on the same level as Prague and Budapest.

Next I would add 2-3 nights to the city of Wroclaw in southwest Poland. Wroclaw is a convenient halfway stop on the train line between Dresden and Krakow.

Wroclaw is probably one of the most architecturally diverse cities in central Europe, the architectural eye candy around the old center reflects every country that has ruled the city over the centuries - from Polish Gothic to Austrian Baroque and German Modernist. Both the local cuisine and culture reflect this multi-layered history too. For comparison, Wroclaw and Krakow are about the same size.

Wroclaw also has Grabiszynski Cemetery, established in 1881 still stands and is quite well maintained and massive. Includes countless graves of WWI and WWII German and Italian Soldiers. Wroclaw (then Breslau) was part of the German Reich pre-WWII. There is also the Old Jewish Cemetery of Wroclaw, opened in 1856, the cemetery's eclectic layout features many architectural forms and styles on a monumental scale -https://kehilalinks.jewishgen.org/wroclaw/Old_Jewish_Cemetery.html

As for churches, just south of Wroclaw is the Church of Peace (built circa 1650s) in Świdnica. The largest timber-framed religious building in Europe, built as a result of the 30 Years War. Known as "The Sistine Chapel of Wood" - https://whc.unesco.org/en/list/1054/

Berlin (4 nights)
Dresden (2 nights) then Ryan air to Krakow (excellent idea)
Krakow (3 nights) then Ryan air to Prague (you did a good job of connecting hard to connect Krakow)
Prague (6 nights) Okay, that's a bit long for me too. Do some day trips. I would go crazy in Prague after 3 full days.

Since you're not adverse to flying ... a suggestion.

The Prague to Budapest flight is cheap, fast, easy and will get you to Budapest in less time door to door as a train from Prague to Vienna. (Budapest 6 nights).

Then you train up to Vienna (4 nights).

Then train to Bratislava (2 nights).

Then fly out of the Vienna airport (about 10 minutes further to the Vienna airport from Bratislava than from Vienna to the same airport) non-stop to Zagreb (and not have to do the long train trip out of Budapest).

Zagreb (4 nights)
Ljublijana (3 nights)
Triste (3 nights)
Venice (2 nights) *I've been to Venice before so I don't feel like I'm cutting it short here
Verona (2 nights)
Milan (4 nights)

BEST CEMETERIES in BUDAPEST (maybe Eastern Europe)
http://fiumeiutisirkert.nori.gov.hu/
http://zsidotemeto.nori.gov.hu/

I haven’t been to all these places, so I have just a few comments. I would add at least one more night to Krakow — it’s fabulous and there’s a lot to do. Perhaps take a night from Prague. I’m not a fan of Milan, so I can’t imagine spending four nights there. The only other comment I have is that this itinerary is pretty heavy on cities. A break in the countryside might be a welcome change of pace.

Are you traveling by train once you're on the ground in Europe? If so,
you have a long way from Dresden to Krakow and then back to Prague.
Maybe consider moving Krakow between Bratislava and Budapest. Or
reorder it to Berlin - Dresden - Prague - Vienna - Bratislava - Krakow
- Budapest. Whatever you do, Krakow is going to be a bit of a detour, but I think you can order it so it's not such a long train ride in
both directions. I would add a day in Berlin. Four days is not really
enough, especially if you are likely to suffer from jet lag on your
first couple of days. I would also add time in Dresden. In addition to
seeing that beautiful city, I think there are two excellent day trips:
one to Leipzig, and one to Saxon Switzerland. Since you mention
cemeteries, don't miss Vyšehrad Cemetery in Prague and Žale Cemetery
in Ljubljana.

I plan to travel by train. Someone else mentioned flying for the longer train rides and I might do that but also considered doing an overnight train right since I've never done one before. (is that actually on people's bucket list? haha)

I haven’t been to all these places, so I have just a few comments. I
would add at least one more night to Krakow — it’s fabulous and
there’s a lot to do. Perhaps take a night from Prague. I’m not a fan
of Milan, so I can’t imagine spending four nights there. The only
other comment I have is that this itinerary is pretty heavy on cities.
A break in the countryside might be a welcome change of pace.

What did you not like about Milan? I used to work in the makeup/fashion industry and Milan was always talked about as "the spot" but that was also years ago and maybe I need to do more research to see how much time I really want to spend there. lol. Do you suggestions for countryside places?

I have only paused in Milan long enough to see the Duomo, but I'm looking forward to a longer visit to see a bunch of its Art Nouveau architecture, and I know the Monumemental Cemetery is often recommended.

Do you suggestions for countryside places?

Try the Kłodzko Valley, located deep in the Sudeten Mountains between Poland and Czechia. I traveled there a few years ago and it was very charming and undiscovered. You can read more about it here - The Blissful Countryside of the Klodzko Valley, Poland (https://www.travelsewhere.net/klodzko-valley-poland/)

Here's my trip report of the region:
https://community.ricksteves.com/travel-forum/general-europe/vicarious-travel-poland-2017-wroclaw-silesia

and my photo album:
https://photos.app.goo.gl/U1z9SUz3E9HsACw47