I can recommend Danny's place for a short stay. It is compact, but clean, comfortable and well equipped. The bathroom/toilet is particularly nice.
It has a good location close to the Naschmarkt, and it is a very quiet apartment despite being right next to the Metro station.
The bed is on a mezzanine floor and is accessed by the stairs that you see in the photo. The stairs are quite steep and might not be suitable for some elderly people. Would I come again for a short stay? Yes.