Deni and her sister were extremely accommodating - we changed the number of people staying in the apartment without any problem, were able to leave for 2 days to go to Santorini and then come back to their apartment in Athens, and left some of our luggage with them for those 2 days when we were gone. We had very late check in times (11 pm and 1 am), but Deni's sister, Gergana, was there to let us in both times. The location is amazing - close to all main attractions in Athens. One small thing to keep in mind is that you may have to check out earlier than usual (around 9 or 10 am) if another guest is coming to stay at the apartment the same day.