In and around Vienna for eight days

Vienna is one of my all-time favorite places. The Vienna Pass is the rare "pass" that I think is actually worth the money. Free admission to basically everything you want to see that charges admission, plus use of a hop on/hop off bus for the duration of your pass.

https://www.viennapass.de/en

We saw a performance of Don Giovanni at the Vienna opera which was a truly outstanding experience. The one thing that I would do differently in Vienna is get better seats to the opera.

Thanks for your visionary insights. I always like reading the words of a prophet.

Sopron has an attractive central area and is worth a visit, but I'd suggest Gyor instead. The travel time is the same from Vienna if not a few minutes faster. Gyor has a larger historic area and quite a few small museums I enjoyed. It's closer to a full-day trip, I think. In addition, Gyor is the gateway to the Pannonhalma Abbey, which might interest you.

If you decide you might be interested in Pannonhalma, I recommend both checking the website carefully and avoiding the weekend and any religious holidays. I headed over there on either a Saturday or a Sunday and found access limited because of a major private religious event. I checked later and didn't see anything mentioned on the website, which is why I recommend just avoiding weekends in general. I wouldn't even rely on the Gyor tourist office in this case, because when I asked for bus directions the afternoon before I planned to visit the abbey, they didn't warn me about the religious event--or about the bike race that meant the bus dropped me at the bottom of the hill, either. I'd guess they just weren't aware that things wouldn't be normal at Pannonhalma on the day I chose to visit.

In truth, if you haven't already been to Budapest (less than 3 hours from Vienna by train), I'd ditch both Bratislava and Sopron and spend every night I could spare in Budapest.

The one thing that I would differently in Vienna is get better seats
to the opera.

I got great seats. I didn't regret it.

The Musikverein is a great venue for classical music. Its Great Hall is Habsburg wonderful and considered one of the finest performance halls in the world.

Take a few days for Budapest. Bratislava is nice for a day, but is so near to Vienna it could easily be a day trip. Budapest deserves a few days if you haven't been.

Thanks for all the very helpful suggestions. We did Budapest a few years ago and loved it. We are trying to expand our horizons outside the great city. The suggestions are very helpful.

Rust on the Neusiedlersee is a nice stop for storks, biking and wine.

Aside from the usual attractions in Vienna, I would be sure to make time to go on a wanderweg, or hike, on one of the hills around the city. There are 13 of these walks, which are well marked, and more information can be found here - https://www.wien.gv.at/umwelt/wald/freizeit/wandern/wege/ You will be in Vienna for sturm time, or young wine, which is very special, so be sure to stop at a heuriger on your walk for a glass.

Lainzer Tiergarten and the Hermesvilla also make for a great afternoon excursion still within Vienna. You can get great views of the city from here.

Vienna is a very bike-friendly city and bikes can be rented for free here - https://www.citybikewien.at/en/. An afternoon biking on the Donauinsel is a great way to see a different part of the city.

I'd highly recommend renting a boat and cruising through the Alte Donau, an old arm of the Danube now strewn with cute cottages and nice views. Exit the U1 subway line at Alte Donau and just to the left you will find Marina Hofbauer where you can rent boats of all types and sizes.

If you are a fan of Art Nouveau architecture, then you can roam the city looking at Otto Wagner sites such as the Majolika Haus, Secession, Postparkasse, Ernst Fuchs Museum, Kirche am Steinhof.

Edited to add that even in September, crossing borders due to COVID-19 might still be a hassle. Keeping day trips within Austria may be a good idea.

If you are not that into opera, you might like the tour of the Opera House just for the history and architecture.

Thanks, Emily and Laura. Very helpful suggestions!

Coincidentally, I will be in Vienna at the same time with my wife and sister. I would add Möbel Museum. My wife and sister are both antique dealers and my wife & I have visited here before. There is also another location near Michaelerplatz that holds and somewhat displays some of the overflow/excess that is not in Möbel. Emily - can you refresh my memory on this? Is that the location or has my memory faded?

Another option for the Opera is to get standing room tickets. I think they were only a couple Euros. I was sure my daughters would not be up for the entire opera, and I didn't want to spend a lot on tickets. The Austria RS guide provide a lot of information on how to do this. We ended up watching the opera until the intermission and then walked around the interior a bit and went out for dessert.

We always enjoy some type of food tour (although the one we did in Vienna a few years ago was not the best; a new guide). But we have been on great tours in other cities, so you can probably find one in Vienna that you would like.

I found a thermal spa in Gyor:

https://www.rabaquelle.hu/

Check it out.

Thanks to all the helpful replies! It's great to have such an informed group willing to share good ideas. Much appreciated!