A friend and I came to Vienna for a conference. Sigrid's place was a 10 minute walk from the arena, which was very convenient. There were good local supermarkets, food places and metro all within 5 minute walk from her place.
Sigrid had provided tea/coffee making facilities and breakfast. Unfortunately, we didn't get to meet her (due to unforeseen circumstances) but she and her family were always contactable and ready to help us when needed. I would definitely recommend her place!
Ps - the bed was very comfortable and the room was large and airy. Great for the hot weather we arrived in :)