re: What can you guys tell me about vacationing in Istanbul?

It's not Constantinople

Go visit all the ancient mosques, great architecture

Stay out of the prisons

Many of the mosques that they actually built borrowed heavily from Byzantine architecture.

Istanbul is great. Places that I'd recommend seeing: Hagia Sofia, The Blue Mosque, Topkapi Palace, taking a ferry across the Bosphorus to the Asian continent, dinner cruise on the Bosphorus, Taksim Square

I spent a few days in Istanbul then flew down to the Mediterranean coast and stayed at a resort. Great experience. The people I interacted with were very nice. Also it's incredibly cheap compared to the rest of Europe.

My uncle worked there, for an oil company, for close to a yr & the one thing he kept repeating was "no one ever gets any medical treatment here". They all fly out of the country for that. Suggest you bring your own legal pharmacy if nothing else.

It's a fascinating place and without a doubt worth a visit. I was there for 6 days in September and that was perfect to see the main sites. With 9-10 days you could take some cool side trips that I was unable to take advantage of.

The city is HUGE... it never ends. I think it's something like the 5th largest city in the world. The good news is the main sites aren't too spread out and are easy to get to.

Lodging
Stay in Sultanahmet for at least half of your stay. This is the historical neighborhood in the old town. A lot of the big attractions will be within walking distance from here. You can also take light rail from the airport to the Sultanahmet stop to avoid traffic and save money. Across the Golden Horn is the newer part of the city. You may want to consider staying a few nights there to get more of a vibe of the modern city instead of the straight touristy area. This is also convenient to restaurants, nightlife, and shopping. Look around Taksim Square and Istiklal street. With that said, a taxi (taksi) ride from Sultanahmet to the new town is cheap and not too far. Also, wherever you stay, make sure it has a rooftop terrace. The views are incredible and it seemed like every restaurant, hostel, hotel, you name it, had a terrace.

Sites
- Blue Mosque, Hippodrome, Basilica Cistern, Hagia Sophia, St. Irene, Sultan Tombs, and Topkapi Palace. You can take care of these between 2 days. They're all in Sultanahmet near each other but some are closed on certain days/hours so plan around that. Hagia Sophia and Topkapi Palace will take up the most time. Audio guides are hit or miss (Basilica Cistern), but anything you can do to educate yourself before going makes visiting these spots much more impactful.

- Spice Market and Grand Bazaar. Also in old town, check these both out. Within walking distance from sites above. The Grand Bazaar is overwhelming. Took me an hour to find a way out of it. Absolutely insane.

- New Mosque, Süleymaniye Mosque, other Mosques. Admittedly, some of these just start looking the same after a while, but the architecture really is spectacular. Make sure you have pants and sleeves on. Two mentioned are in old town.

- Galata Bridge walk from old town to new town. Check out all the old fishermen and fish restaurants down below.

- Churches/Christian Sites. If you are Christian or have any interest in Christian history, there is a ton of it in Istanbul. Aside from Hagia Sophia, the first large Christian cathedral (built 1500 years ago!), there are other churches that still remain, unconverted to Mosques and not torn down. Chora church is the most recommended. Also, take the short taxi ride to the Fener neighborhood to check out the Greek Orthodox patriarchate. In a way, it is the Orthodox equivalent to the Catholic's Vatican, as it is where the Patriarch is still seated even after the sacking of Constantinople 500 years ago and gradual population decrease of Christians to essentially zero now. Small church but it is beautiful on the inside.

Activities
- Whirling Dervishes. A religious dance ritual. Technically not an entertainment performance, but a few times a week there are venues around town holding the ceremony for tourists to watch. Mesmerizing. I did the one held at the Sirkeci Train Station. Old town near Spice Bazaar if I remember correctly.

- Bosphorus Boat Cruise. Awesome views. You can either do this on the cheap by taking a commuter ferry to the Asian side or through a boat tour company. Be sure to haggle if you go through an actual tour.

- Hamam/Turkish Bath. If you're the least bit adventurous and OK with submitting the control of your body to a large Turkish man... DO IT! My most memorable experience by far was this. You don't travel half way across the world to stay in your comfort zone. Cemberlitas is the one I went to.. not far from Sultanahmet.

Eating
- Sultanahmet is pretty much limited to overpriced places catered to tourists. Even with the tourist prices, a bunch of the restaurants around the Blue Mosque are still fine and offer great rooftop views. Definitely check out Doy Doy for a place with a more casual vibe, lower prices, and still fantastic views.

- Street food is abundant. And delicious. And cheap. Doner kebap. Watermelon, grilled corn, sesame pretzel looking things. Buy a fish sandwich from the colorful boat near Galata Bridge.

- Nevizade street is a small alley off of Istiklal street, which is the heart of the modern city. Tons of places to choose from. At the very least, walk down the alley one night. Plenty of bars in this area too.

Side Trips
- Princes' Islands. Perhaps my favorite day was a trip to the largest of these islands in the sea of marmara. Take the fast boat out there. It takes 45 minutes or so. Rent a bike (no automobiles) and explore. Hike to the top and check out the old Greek Orthodox chapel and amazing vista. Reward yourself with a beer and some mezzes. Bike to the back side of the island and hike down to a tucked away "beach". Relax. Maybe consider spending a night on one of the less busy islands if you're with a S/O.

- Other trips include Cappadocia, Ephesus, Troy... I'm sure there are others. We didn't have time to explore the rest of Turkey but with 9-10 days, you should explore beyond Istanbul

Oh boy, I just wrote a lot and need to get back to work. Hope this is helpful!

One other thing I didn't mention...

Turkish people we came across were generally very friendly and hospitable. Some openly seemed to have a disdain for the huge influx of Arabs or at least a fundamental misunderstanding with their lifestyle and more radical version of Islam. Found that interesting.

Those people are creepy and wont leave you alone, especially the women. Turks are mean too.