I’m planning our next trip to in late September/early October, 2026. We are avoiding the Octoberfest in Munich so this is what I’ve planned so far. We have travel to Europe many times but not to these countries. Not including travel time I am thinking

4 nights in Budapest
4 nights in Vienna
3 nights in Salzburg
3 nights in Munich

We are active older travelers and enjoy having a slower pace where we can soak in the architecture, culture, arts and food scenes. Would you suggest changing the itinerary based on your experience?

That seems a very reasonable plan/allocation of time. If one were doing any day trips I might switch one night from Salzburg to Munich -- but that is just a minor quibble and the 3 / 3 you have is fine.

Your itinerary looks well-balanced and not rushed.

Does your itinerary leave you with?

3 full days in Budapest
3 full days in Vienna
2 full days in Salzburg
2 full days in Munich

If so, that seems reasonable, though I might drop Munich and spread the days over Vienna and Salzburg, or a stop in-between if you are traveling by train. (Just my opinion. Munich never intrigued me the way the other three destinations had). I'm assuming you are traveling in mid-to-late September? There will likely be many grape harvest festivals (at least in Budapest and Vienna) to enjoy.

I wanted more time in each city. For my interests: 4 days (5 nights) in Budapest (particularly if you are recovering from jet lag while there), 5 days (6 nights) in Vienna, 3 nights (2 days) in Salzburg, and 5 nights (4 days) in Munich. That said, it really depends on what you want to see and experience. You would, I think, do well to plot things on a calendar.

The OP says "Not including travel time . . . " so I was assuming he actually meant 4, 4 , 3 and 3 full days in those cities.

Could be! I thought the "travel time" in question was getting to Europe and back. Perhaps the OP can clarify?

It's been decades since I've been to Salzburg and Munich, so I really can't comment on those cities, and we haven't been to Vienna yet. Last September we spent 5 nights, so 4 full days in Budapest, and we could have used an extra day in Budapest. But there is never enough time . . . So, for Budapest, 4 nights is the absolute minimum, but if you could add an extra night to Budapest, that would be even better. And we didn't do any daytrips from Budapest. It's a gorgeous city with so many interesting sights, and it's a wonderful and fun city just for wandering and exploring, too.

I looked at the OP's itinerary and thought about the friends who visited while we lived in Vienna. They all wanted to see and do Vienna and Budapest in a week or so, and they all ended up just seeing the touristy things. That was their goal and they achieved it. Perhaps that is what the OP wants.

Personally I would not spend two weeks on their itinerary. But everyone travels differently.

I agree with kja, Karen and fourtravel, we had 6 full days in Budapest in April 2024 and could easily have filled in another day or two. I haven’t been to Vienna in some 15 years, but I think it needs more time for a leisurely exploration. Some fabulous museums there, so perhaps I’m prejudiced.

BTW, we’re considering spending Thanksgiving week in Vienna this November, if that gives you an idea of how long some of us would spend there.