Only 4 days-where do we stay?

I've been to all of those except Hallstatt. All are worth visiting for the factors you are looking for.

Maybe pick two and do two nights each?

I can't recommend which two. Innsbruck is probably my least favorite of the four, but you'll get great bang for your buck wherever you go.

With only four days, I would pick Vienna & Salzburg. They’re easily connected by train; I think it’s about 2 1/2 hours. Vienna has the elegance and nice museums, and Salzburg has the quaint old center with music options and an easy city to enjoy. Bonus if you like the Sound of Music type setting.

It all depends on what you guys like not what any of us like. Salzburg for classical music, the Sound of Music and beer gardens, Munich for beer gardens, Hallstatt for the salt mines. Only driven thru Innsbruck and Graz.

Salzburg. From there you can easily drive to Hallstatt, Berchtesgaden and Werfen as day trips if you wish. Each has plenty of interesting sights. We’ve spent 10 nights in Salzburg over two trips and would return in a heartbeat.

How much time do you have in total? Most people try to squeeze too much into a small time frame, underestimating travel times.

Salzburg. 16 nights over 3 visits. I was hoping to do against next year, but DIL wants more time in Italy

I've probably done my 25 nights in Salzburg over many visits over several decades. For what you are describing, it's probably clearly the right choice along with Vienna.

I'm over it though, been there done that bought some bicycle tires. It's not an inexhaustible place like Paris etc.

But it is lovely, and you should go visit :)

Since I know Vienna the best among the others listed, I would suggest all 4 days to be spent in Vienna, a captivating and fascinating city, sociologically, culturally, musically (apart from the waltzes) , when visiting and exploring it as a whole, walking , using the combination of the subway and the trams.

If you are asking about spending 4 full days after dep from Vienna, then it's a toss up between Munich and Salzburg.

I'm with Fred . Four days in Vienna ? I've spent over three months there in the past number of years , and it is still not enough . The other locations are great , but four days ? don't leave Vienna !

"and it is still not enough." Ain't that the truth !

Likewise with Berlin and, course, Paris. Over the years, especially, since the post-retirement trips to Vienna, I would have to go through my calendar notebooks to arrive at an accurate and precise count of nights spent in that fascinating city, to which I am revisiting this summer too.

I’m confused by your question. Four days after Vienna or four days including Vienna?

I’m confused by your question. Four days after Vienna or four days including Vienna?

This. If it’s 4 days total, just stay in Vienna. If 4 additional days, I’d say spend this 4 days in and around Salzburg.

In another post the OP said

My daughter and I are staying in Vienna for 3 weeks, a little less with some day trips. Where is the best area to stay that would allow us to take mass transit and see the most of Vienna’s beauty and activities?
Thank you
Ps we leave in 15 days!

So I'm guessing it's 4 days after Vienna. And they may already be in Austria!