First, I would 100% recommend to stay at Evrim's wonderful apartment! everything looks even better in life and there is everything you might need in your trip!
The apartment is very stylish, warm and location is 5 out 5: lay back Nisantasi which is full of different cafes is just 3 min walk and never sleeping Besiktas is 5 min walk down the street on opposite direction. If you need to use a public transport there are bus stop and metro station ~10 walk from the apartment.
The apartment itself is very specious, so you can have you privacy and also there is plenty of space if you work remotely with a good internet connection.
and Evrim was one of the most friendly and kind host you could meet!
great place to stay in Istanbul