Austria advice

We really need to know what sort of sightseeing you want to do. For example, Vienna is especially rich in art museums.

In addition, "fall" could be late September or late December. More-precise timing would potentially affect how enjoyable days full of outdoor activities might be.

I suspect when you write "3 or 4 days" you really mean "3 or 4 nights". For me that would be a short visit to Budapest as the first stop on your trip. How well do you handle jetlag?

Budapest-3 nights
Vienna - 3 nights
Wachau Valley (Melk, Durnstein & Krems) -2 nights
Salzburg- 3 nights (w/ daytrip to Berchtesgaden National Park).
Munich- 3 nights

Skip Innsbruck because the other destinations offer so much more.

You can stop in Bratislava on the way to Vienna, store your luggage and see the old town center in a few hours. However SOPRON, on the Austria-Hungary border, is much more interesting.

Thinking it through a bit, Arrival day isnt worth much with a half day and jet lag so,

Budapest 4 nights (minimum as arrival city, 5 nights prefereable but i know you only have so much time). The tourist area in Budapest is also several times larger than the tourist area in Vienna so that has some bearing on things too, unless you are a museum hound in which case you want to maximize the time in Vienna. See, there is no off the cuff answer to this stuff. Here are some videos on Budapest and the same guy that did the first video here did two on Vienna that are pretty good too: Favorite Tourism Video of Budapest https://youtu.be/1nd5AtZIrTk?feature=shared Anthony Bourdain describing how visually pleasurable Budapest is https://youtu.be/0nd9DuDGCz0?si=aa0c19KaJHEtabkX

Vienna 3 nights (minimum 4 nights preferable)
Salzburg 2 nights max given the other destinations.
The others I cant help you with.

As for stopping in Bratislava on the way from Budapest to Vienna. That would be the Prague train (not the Vienna train) then you still got to get to Vienna. A lot of work and a lot of extra travel time to see something that isnt worth losing one day in Budapest or Vienna for when you are on a tight scehdule. Bratislava old town exists for one reason, tourism. Its has no life beyond tourism. Out of the old town is interesting in places but now you are talking about a much more complicated visit. Sopron? I would love to hear what the person saw or did in Sopron that was better than another day (with limited days) in Vienna or Budapest. Not a good idea. Seriously, I might have missed something.

Budapest - 3 nights
Vienna - 5 nights
Wachau Valley (Melk, Dürnstein & Krems) - 1 night
Salzburg - 2 nights
Munich - 3 nights

For me, the Oktoberfest is not particularly appealing. Hordes of people in fancy dresses trying to get drunk as fast as possible from weak and expensive Bavarian beer. (Austria and Czechia have a much greater variety of tasty beers.)

I would suggest focusing the number of nights spent in Austria to be done in Vienna, at least 5 full days in that city. Obviously, this depends on your level of interest in the culture, architecture , language, history, etc of Vienna, spent more than a week there this time, and never tire of returning on every trip. It all depends what you're after.

Re: I am not a fan of Oktoberfest, never was but that does not mean skipping Munich, spent only a week-end, 3 nights, in Munich this time the end of June and tracked down, luckily too, a few very esoteric and significant historical sites .

Thanks for the advice. You guys gave me something to think about. Jetlag isn't really a thing for me or my wife and we usually plan to book some type of tour for the afternoon/evening we arrive. It gets us out and helps us reset our internal clocks. Oktoberfest is happening for us. Hotels are already booked and we are meeting 6 friends in Munich. I've done Munich twice already so this trip will be all about Oktoberfest and having a bit of fun. It really came up since there is a nice direct flight back from Munich to Boston so I was going to need to go through there anyways.

jpfitzy7, im with you on Oktoberfest anf itd tge only time during tgr year that I can wear a fancy dress and not have people look at me funny.