Elif and Marco's apartment in Firuzaga is perfect for 5 people. We were two adults and three kids and it was just right. My parents came to stay for a couple of nights and we thought a folding bed or an air mattress would have made it just right for an additional guest. The apartment is nice, very central, close to bunch of nice cafes and restaurants and sightseeing. The only thing is it is right next to the mosque which means your hear the prayer every morning at 5 am :) The street is also loud pretty much all night but if you close the windows and turn on the AC, you can escape that. We had a great one week vacation in Istanbul and enjoyed our stay at Elif and Marco's apartment.