We stayed twice at Sarnic suite (also called Turquoise apartments, I think). First time was 4 adults and 1 toddler. This was a bit of a squeeze with 2 adults and a cot (thank you!) in the main kitchen/lounge area and Grandparents sleeping 'downstairs', in quieter room but aware of steep stairs....
BUT 2nd time we were just 2 adults and 1 toddler which was much easier as toddler slept upstairs ;-) I think there may have been bigger apartments upstairs from us.
The Apartment is Fantastic: very clean, beautiful décor, fully equipped kitchen, even with a microwave! The living space got quite hot/stuffy quickly (we kept the windows closed) and the aircon worked well. The shower was good, with plenty of hot water and there was even a little cupboard to put our toiletries in.
The person who met us with the keys spoke great english and was very friendly and helpful. The apartment is up some stairs and so just off the ground floor, with the bedroom down some tricky stairs and just below road level. The room did get a bit noisy with car traffic and kids playing outside but it didn't go on until too late!
Saban answered his text msgs and quickly arranged a well priced transfer to the airport on our departure.
Saltanahmet neighbourhood is a mixture of falling down houses and 5* hotels and Sarnic suites is located down one of the side streets, about 2min walk from more luxurious hotels and a busy hub of restaurants. Ottomon Tulip hotel is right across the narrow street if your taxi can't find the address ;-) I felt safe and happy walking around by myself, and it took only 15mins to walk to the Blue Mosque area.