My partner and I absolutely loved our time at Sarka's place. It was exactly what we were looking for and turned out to be even better than we expected: cozy, clean, in a good location, and with little treats from Sarka and Michael. They were very accommodating and helpful.
Going for a burger and beer at U Kurelů is a must, and we also highly recommend 'Donut Shop' which is not too far from the flat. There are art galleries all over Prague that are worth popping into. DOX is one of the coolest contemporary art museums we've ever been to. It's on the other side of town, but you can get there in about 15 min with Uber. If you go, check out the "open archives" section - great books & cheap artsy postcards.
Enjoy Prague! It's a magical city!