I can highly recommend Katrin and Fritjof’s place! I have had a wonderful stay with them in their beautiful home and they are such friendly people - I feel so welcome. The guests have access to their own little kitchen which is very well-equipped, and the bathroom is nice.
Dahlem is a quiet, residential area and there’s a good bus service from just outside the house - the tube station is also only a 7 minute walk, so whilst the house is not central, you can be in the centre of Berlin in half an hour! There are plenty of shops around the tube station, too, so everything is close. It’s a very nice area, feels very safe (even at night) and there are lovely places for walks / runs near the house.
Thank you for a wonderful stay!