We will be in Vienna in Sept. Do we need to really book a "tour" or could we navigate ourselves? (only 3 days)
The only tour that we booked in Vienna was for the Wachau Valley. We found Vienna very easy to negotiate on our own in 2015. We are unapologetic museum freaks and the Vienna Pass was great for us. We used the included HOHO pass to reach the few places we couldn't walk to.
Public transport is excellent, safe, and easy to use in Vienna. Buy a 72-hours-pass which gives you unlimited access to tram, subway, bus, train, etc. Don't waste your time walking longer distances.
With the Vienna Pass you drive yourself into a hurry, panting from museum to museum, just to have its cost pay off by utilizing the reduced entry prices. The HOHO busses limit you certain routes to places in certain order.
Enjoy Vienna, less is more, and stay longer the next time.
You might want to check out the walking tours offered on the TI office website. They are reasonably priced and have several different focuses. With just 3 days, you ‘ll want to use your time efficiently. I agree with the poster who advised more days next time. We had 5 days on our first visit, and liked it so much that we went back the next year for another week.
There's no "need" to book a tour unless you want one. As said above, Vienna has excellent transit and much of it in the central areas is walkable. With Rick's book (or another guidebook), you can do it yourself.
I took two walking tours; one (a general introduction) was good, the other (on Jewish Vienna) was excellent. A walking tour is a great way to get started, even if you are doing the rest on your own.
Rick has some free Vienna audio tours, which you can get on his app, or else download and preview here: https://www.ricksteves.com/watch-read-listen/audio/audio-tours/austria-germany