Me and three of my friends spent four nights in Sultanahmet Gardens Family Suite. We felt quite comfortable there. It's nicely arranged and has got lots of space and bedrooms. The house is very close to Hagia Sophia and the Blue Mosque, you can easily walk there.
Tansel is a friendly host and was very fast fixing the shower when it got broken on a Saturday morning in Ramadan.
I gladly reccommend Tansel's Sultanahmet Gardens Family Suite.