In Istanbul we stationed ourselves in the Sultanahmet neighborhood or the “Old City” at the Seven Hills Hotel about a five- minute walk to the Ayasofya aka Hagia Sophia, Cisterns, Blue Mosque and Topkapi Palace. These places are the main tourist attractions and if you only have a couple days in Istanbul it is a very convenient area to stay in. Some of the other places not in Sultanahmet that I highly suggest visiting are the Grand Bazaar (goes without saying), Galata Tower, Istiklal (the New City), Taksim Square, the Asia side of town, Chora Church, Ortakoy Mosque (my favorite mosque) and to take a Bosphorus Cruise.
If you like history, food, shopping and are looking to go somewhere that will both excite you and welcome you with open arms then go to Istanbul! Someday when I return to Turkey, I would like to visit Ephesus, Cappadocia and head north to the Black Sea.
On another note- we felt completely safe. There is a lot of buzz about safety traveling in Istanbul but we never once felt insecure. Obviously be sure to take precaution when traveling anywhere but overall I felt safer in Istanbul than a lot of western cities.