A good option in the Boyoglu area, near Galatoport. There is no need to go uphill. There is a shop nearby, right in front of the hotel entrance. A hotel with apartments, with a 24-hour reception. There is a Russian-speaking employee, his name is Yakup. The rooms are quite passable. You can cook by yourself, especially if you have a large family, because the prices in Istanbul for food in cafes are now cosmic. The more people there are, the more expensive it is, so it is profitable to cook.
We stayed with a family, with a small child, a great place, pleasant staff, excellent transport accessibility. The room was clean and comfortable enough.