I had an awesome stay for 4 night's at Isabel's place, super comfy with everything a traveller may need, plus a big bed and a big desk. Isabel is a very nice and welcoming host!
The location is also amazing, both short- and long-distance trains are just a stone-throw at the Berlin Südkreuz station (8min shortcut leads through the stairs at the northern end of the long-distance platforms). In addition very nice walks or bike rides to the Gleisdreieck park, Bergmannkiez, Viktoriapark Kreuzberg (the actual Kreuzberg hill with a view), the formar Tempelhof airport, Schöneberg. A lot of nice cafés and restaurants are in the mentioned areas, accessible by a shorter or longer walk (through parks and quiet residential areas), or a very short train ride.