I stayed in Istanbul with my wife in holidays.
We've stayed in Istanbul for 4 nights and then we went to Cappadocia for 3 nights and finally returned to Istanbul for 3 more nights.
We were hosted in Senatus Hotel during all our time in Istanbul.
Senatus defines itself as a boutique hotel in Sultanamet and in fact it really is if considered within the context of Istanbul. Although, not a boutique hotel as we have imagined it in the first place when in comparison with other boutique hotels where we've stayed. Nonetheless, this should not be taken as a low point of the hotel it is just a specific issue from our expectations and experiences.
Regarding the hotel, our first advise would be to not let yourself have a first bad impression of the hotel due to the first contact with its owner/manager (a large guy at the reception) who may not seem very friendly either due to its poor english or to a shy personality. You shall overcome this as Senatus will give you a great experience in Istanbul.
Senatus is wonderfully located deep in the heart of Sultanamet with all the main attractions within (true) walking distance.
The rooms are superbly clean with simple and modern decoration. The towels are changed everyday!
Our room was in the ground floor next to the elevator, as I saw from the glimpses that I had from the other rooms it was not a very good room (small with no natural light), although from there you could have wireless signal from the internet which should be only available at reception. If this is a main issue to you, you should ask a ground floor room, if not try to avoid in order to get a bigger room.
The breakfast is simple and have all the basics to a continental menu and plenty turkish dishes with a lot of mixtures. This is funny at the beginning of your journey but after some days you may get a little bit tired of it due to the lack of variety if you prefer to keep a continental menu.
The staff with exception to the ones working at the reception do not have a very good english and the ones at the restaurant struggle sometimes to attend simple requests. Nonetheless, everybody makes their best efforts for you to feel comfortable and to solve any issue that you may have.
For example they confirmed our transfers and kept our luggage during our stay in Cappadocia without charging any extra fees.
If we return to Istanbul we will definitely return to Senatus due to its central location and cleanliness of the hotel.
Finally, we stayed in Istanbul during the Ramazan and it was a great cultural experience, we did not have any problems with drinking or eating during the day. Would recommend everybody to experience Istanbul during this holiday period and to have dinner in the park between the Blue Mosque and the Aya Sofia together with locals after sunset.