We spent a week at the Four Seasons in Istanbul during Ramazan and it was amazing. Simply amazing.
It's right in front of Hagia Sophia and Topkapi Palace, just steps from the Blue Mosque, too. It was to die for. The hotel was outstanding in every way. In fact, although all Four Seasons are spectacular, this one is supposedly the second best hotel in Europe! The thing with Istanbul is that there is the old city and the new - and the traffic between the two was horrendous, and most of the cool stuff is on the old side, so I would advise staying there as we did. We talked to a ton of people staying at hotels on the new side (like the Ritz) and they were really bummed about having to deal with the traffic. But, obviously, the location all depends on your budget.
We were there only 4 days (we could've stayed for 4 weeks!), and had a private guide and driver all four days who picked us up from the airport and drove us around the city. The guide was a young Turkish man who went to Robert College in Istanbul and then to UVA here in the states, so he spoke great english. If you get a guide, make sure you get a licensed one, as the guides in Turkey are required to be licensed. He arranged the private car and the driver, and helped plan the itineraries, and ate lunch with us. He became like a friend! (In fact, I really need to email him!!) But, he was amenable to doing whatever we wanted, when we wanted.
We did all the normal stuff - The Blue Mosque, Topkapi Palace, Hagia Sophia, the Cistern, Galata Tower, Dolmabache Palace. We also took a private boat ride up the Bosphorous, and that was a blast and just beautiful. Istanbul is a city surrounded by water, so to go there and NOT be on the water seemed like a crime! We also did the Grand Bazaar and Spice Bazaars and bought a rug!
The food in Istanbul is awesome! We ate at the Four Seasons for dinner one night and it was incredible, as were the breakfasts we had each morning. We ate lunch at a kafteh place in Sultanahmet, too, and that was great. Hamdi Restaurant was great food and service and the view is stunning! You must go for lunch to take full advantage! We also ate baklava at Haci Bekir and had the freshest seafood you can imagine at
Balikçi Sabahattin, near out hotel. Soooo good!!!
We also did a lot of non-touristy things, like visit Bagdat Street for coffee and shopping. This was on the Asian side, and it was cool to go to that side of town and see the area. We also hung out at the area known as Beyoglu and Istiklal Caddesi. I highly recommend that area - lots of cool shops, bars and restaurants. Very hip.
I just so enjoyed the atmosphere of the city that I could stay forever!!