We had the luxury of staying at Seven Dreams Hotel Istanbul for 4 nights from march 12-march 16. It has a perfect location in Sultanahmet right next to the Four Season's Hotel, the Blue Mosque and the Hagia Sophia.
Everything was perfect. The rooms large and airy, the service was excellent as everyone was there for us at all times. It was definitely one of the best hotels we have ever stayed at. Do not expect a grand commercial hotel as this was a boutique style hotel with all the amenities of a large star chain. Also the rooftop Restaurant/Bar has the most amazing view you could possibly imagine.