3 weeks in Central Europe

I suggest skipping at least one night in Germany.

Krakow isn't a day trip from Warsaw, but it cannot be missed.

First of all, most of your trip is in Central Europe.

Instead of Braunschweig, consider Dresden and Nuremberg. Also, Krakow, Poland is my choice over Warsaw and I have been to both cities.

One night in Munich doesn't make much sense.

Poland is quite out of the way in your itinerary. I would leave it off and return for another trip. Kraków is not a day trip from Warsaw, and definitely deserves a few days to itself. I would put Kraków over Warsaw but I did love Warsaw and def think it’s worth a visit. Is there a reason you’re trying to squeeze Poland into this trip? Have you looking into visiting Wrocław? It’s closer to Czechia and Germany and might fit in better with your itinerary.

The trains from Vienna to Prague are pretty straight forward. Multiple a day and take about 4 hours direct. Unless you were thinking trains from Kraków/Warsaw to Prague, then yes this is a very long journey. I believe there is a night train that goes from Warsaw to Vienna maybe Warsaw to Prague. But I would look into flights if you decide to do this. Also look into FlixBus for some of your routes as the departure times or prices might be favorable. (Just make sure to buy in local currency. It’s cheaper)

Unlike many I am not averse to short commuter flights when traveling.
So since you mentioned Krakow and an interest in Eastern Europe I would look at flying into Berlin, train to Braunschweig, train to Prague, flight to Krakow (under $100, about an hour, non-stop on Friday and Monday). Then fly to Budapest (under $100, about an hour, non-stop on Tuesday, Thursday and Saturday). Then train to Vienna; then Salzburg if you want and home from Vienna.

Maybe

2 nights Berlin and train on to Braunschweig
2 nights Braunschweig and train back to Berlin
2 nights Berlin and train to Prague
3 nights Prague and fly to Krakow
2 nights Krakow and fly to Budapest
4 nights Budapest and train to Vienna
2 nights Vienna and train to Salzburg
2 nights Salzburg and train to Vienna
2 night Vienna and go home

This is actually an excellent cross section of a lot of cultures. No two places have much in common.

That's a very busy itinerary from James E, but congratulations to him for working Budapest into it! ;-)

Either of your plans have you moving between cities on about a third of your available days. That's a lot of time spent getting places instead of being there. I certainly don't see the point of a second visit to Berlin, for just one night, in #2.

Of course I worked Budapest into it!! Go to Eastern Europe and not see Budapest? Might as well stay in Central Europe! 🤣🤣🤣 (and it got him to Krakow in a reasonable manner).

As for busy? I have learned that each to their own. What works for me isnt going to work for someone else. The OP had a series of 3 night stays and I just copied that. If it were me .... maybe I would do that trip but probably would drop Salzburg. But to be honest for the first few trips someone makes i sort of like the idea of busy schedules (i did it many, many years ago). Its a good way to figure out what you enjoy, then you can return if you want to spend more time. I remember my first trip to Vienna was planned to be pretty long. After 3 days I just wanted out. So we winged it and got train tickets to Budapest. Didnt know a thing about Budapest but it had to be better than Vienna (nothing wrong with Vienna, just didnt "speak" to us).

I agree with James E's itinerary. But I'd cut off the detour to Poland and use more time in Munich.

Itinerary #1! You get Rothenburg rather than backtracking to Berlin, and Munich and Salzburg instead of Warsaw. Maybe consider moving one Salzburg night to Vienna? For what it's worth I haven't visited Braunschweig, Rothenburg, Vienna or Warsaw.

If you want to cut down on number of places to avoid using so much energy checking in and out and traveling, I would cut out Salzburg. I've been to both Salzburg and Vienna and much preferred Vienna. I would also go to Krakow instead of Warsaw.

I agree with cala about Krakow and Vienna. Salzburg didn't do much for me either, but I never cared about The Sound of Music. And James makes a good point about trying lots of places on your first trips before settling into where you enjoy most. And, as he knows, I'm a big Budapest fan too, and appreciated his good advice about visiting there years ago. I believe Paris is sometimes considered "the Budapest of the west."

Krista, you're getting lots of good and contradictory advice here from well-intentioned people, and if you follow all of it you'll go nuts and need a month! So do the trip that makes sense for you, and assume that you'll return to the places you enjoy most. But I still have to ask, what's with the additional night in Berlin in itinerary #2?