Ulli's house is a great place to stay for a small group - it's very spacious and the bedrooms are very generously proportioned - you won't be tripping over your suitcases! We ate out every night but the kitchen is well-equipped should you wish to cook. The house is a 15 minute walk from the S-Bahn/U-Bahn and it's a short ride into Alexanderplatz. Being in the suburbs means that the area is lovely and peaceful compared to the city centre.
We'd definitely stay here again!