Here are a few suggestions, in case it’s helpful. Gives me a chance to daydream about Istanbul 🙂
Take a ferry to Kadiköy on the Asıan side and go to the famous Çiya Sofrası restaurant:
Get a balık ekmek (fish sandwich) on the pier at Eminönü (on the tram line).
Have a coffee and play backgammon by the water in Beşiktaş or Ortaköy or Bebek or Arnavutköy (all neighborhoods along the Bosphorus on the European sıde).
For a spectacular view and somewhat dressy dining experience, go to Zeyrekhane next to the church of Christ Pantokrator:
I love the dürüm döner sandwiches (the dürüm are the ones wrapper in flat lavash bread rather than a roll-type thing) from the joint at the top of Istiklal street in Taksim square.
Further down Istiklal street, off the right hand side of the street if you are walking from Taksim Square to Tünel, there’s an area called Nevizade where they serve delicious fried mussels in bread with a garlic sauce (street food, which, incidentally, I have never gotten sick from eating in Istanbul). Also you can buy delicious “medya dolma,” or mussels stuffed with rice anywhere along Istiklal.
Sights: Your guidebook will tell you what you need to know, but for what it’s worth my favorite mosque is the Rüstem Paşa Camii very close to the Spice Bazaar, and I love the Chora Church mosaics in Edirnekapı:
Shops: In the grand bazaar if you are looking for carpets go to Adnan and Hasan. Hasan is a delightful person with beautiful, beautiful rugs.
For antique copper/brass things, go to Murat Bilir at L’Orient. He is also a delightful person, knows everything about this artwork, and has beautiful things in a range of prices.
Finally, if you have the time and the weather is nice, take a boat to the Princes’ Islands in the Sea of Marmara!