We booked direct with Celebrity and then organised our flights for London Heathrow and hotel stay in Istanbul ourselves.
We had visited Istanbul before so returned to the same hotel, the Best Western Empire Palace. It is a small friendly hotel with all you need without breaking the bank. It is on the tram line thorough the tourist area with many restaurants directly outside the hotel. You can walk to the main tourist area at the Hippodrome and the Underground reservoir in about 8 minutes or get the tram to what was the best entrance to the Grand Bazaar.
The hotel made us feel very welcome. A buffet breakfast is included and provided all we needed to start our day without being too lavish. eggs, cereal , delicious Turkish breads, jams and honeys etc.
We were worried about obstructed view but it was no problem at all.