This is my second trip to Istanbul and my goal was to dine at the Orient Express restaurant at the Sirkeci train station. Elite Kasseria is the best choice for the price offered and the location. It is a short 5 - 10 minutes' walk to the Sirkeci train station, and even closer is the Gulhane tram stop where you can take the tram to the major sights in Istanbul, like the Blue Mosque and the Hagia Sofia at the Sultanahmet stop.
However, if you were to take the metro from the airport it would be a little tricky as there are no metro stations nearby so you will need to change to a tram.
The room I booked with two single beds is small so if you have two people with big luggage you might need to fully utilise the floor space. After staying in another country with leaky showers, this room is God-sent, with a clean shower and toilet. The sheets and floor are also pretty clean. Overall, good location, non-fuss and clean.