A high bucket list thing to do in Vienna is to eat the famous sacher (pronounced "soccer") torte. The cafe is located in the Sacher Hotel. Earlier this week I counted over 50 people lined up to get in at 5: 00 P.M. on a very cool evening. In warmer weather I imagine the line can get longer. There is a way to avoid the line.
Within sight of the Sacher Hotel is the Hotel Bristol. The Sacher Group purchased the Hotel Bristol a few years ago, so you will find the sacher torte on their menu. Both hotels are 5 star hotels, so if you are going to drop in, smart casual attire would be prudent. The Sacher Hotel has a person immediately inside the main entrance to greet you (and turn away non guests). If you happen to get past him, there is another uniformed person standing in the middle of the hall waiting to do the same. In other words, you will not get into their dining room. However, this is not the case at the Hotel Bristol. We have just returned from a week's stay at the Hotel Bristol, so these instructions are accurate. (early October, 2022)
The doorman on the street at the Bristol does not stop anyone. Just walk through the revolving door. Once in, keep walking straight ahead. The small lobby you enter has a concierge desk on the right. Just pass it. Keep going straight into the next area that has the reception desk on the right. Ignore it and walk straight ahead to the dining room. If there is someone at the podium, just tell him that you are there for lunch. If no one is at the podium open the door (they are usually kept closed) and find a table. When the waiter comes just tell him that you would like a coffee and a sacher torte. I saw people using credit cards in the dining room, so you do not need to be a hotel guest. Why waste 1-2 hours standing in line at the Sacher Hotel cafe when you can walk right in just 100 yards across the street. Time is valuable when you are travelling.
BTW: The torte is decadent. You really should try it. If you decide to bring some home, they told me it had a shelf life of 18 days. They ship it all over the world. They sell three sizes in their shop that is around the corner from the big line up. There will be no line to get into the shop. Enjoy!