Originally Posted by ISTFlyer

Depending on the price, Park Inn Odayeri would be a closer but cheaper option ( compared to the YOTEL ).
Hilton Kayaşehir would also be a good spot, both reachable by taxi and Havaist bus in 30mins.
Hilton Maslak would also be a 30min taxi ride but it's also closer to the city and has direct metro access to the city.

If you want to earn points or use status benefits at a Hyatt hotel, go for the Hyatt Centric Levent ( avoid if planning to leave the hotel from 15:00 to 20:00 - 35mins taxi ride if no traffic ) or Hyatt Regency Ataköy ( 40mins taxi ride if no traffic )
If you're looking to earn points on a specific chain other than Hyatt, please feel free to write it, so I could also give further information.