I lived in Istanbul 2 years, have visited many times over the past 30 years, and have lived in Turkey a total of 15 years. I don't know about the current photo taking restrictions, but you can get a lot of good information and links on the
government tourism ministry.
Istanbul -- If you put in a long day, you can visit 4 interesting sites in the same area: Topkapi Palace Museum (Topkapi Sarayi), the Aya Sofia Museum, the Blue Mosque (Sultan Ahmet Camii), and the underground cistern (Yerebatan Saranci). Topkapi (Gun Gate) is a different area in Istanbul, so be sure to tell the taxi driver you want the "Topkapi Saray" or better yet, just ask for "Sultan Ahmet" or "Aya Sofia" to get you in the general area (I learned this the hard way). Another interesting palace is the "Dolmabache" palace on the Bosphorus, worth a half day guided tour.
If you are interested in christian heritage and history, you can visit the Orthodox Patriarch facilities and chapel in "Fener". Ask for "Patriark Hane".
The passenger ferries that work the Bosphorous have very cheap fares, and provide good photo opportunities. Sometimes, there are inexpensive cruises up and down the Bosphoros on these boats. You can also get ferry boats to/from the islands in the Sea of Marmara. They are worth a visit.
I also found a couple of train stations rather interesting. The "Sirkeci" station near the Galata Bridge on the European side was the terminal for the Orient Express when it was still running Paris-Istanbul. On the Asian side, Haydar Pasha (also a passenger ferry stop, easy to get to) is of rather interesting historical architecture.
Shopping areas. The Grand Bazaar is the largest and most famous; and is excellent for photos. I also like the Egypt Bazaar (Misir Charshisi), full of spices, candies, and other tasty foods. If you walk between these two, there are a lot of street vendors and small shops providing more photo ops. The main shopping area in Istanbul is Galatasaray. There's a tram that runs through the area from Taksim Square (center of town with all the 5 star hotels).
Dalaman -- I've not traveled that area very much, but have spent considerable time in Marmaris. It's a nice city with a beautiful harbor.
I have a number of photos posted on my
Turkey Expo Gallery . You may find them interesting. Turkey is a fascinating country and I'm sure you will enjoy your stay. Email me if you have any questions.