The Mediterranean and the Aegean sea regions of Turkey are filled with a very wide assortment of boats and large yachts. However the types of boats that seem to interest many are gulets. Since they are unique to Turkey, it is limited to where else you can see them cruising in other parts of the world.
Gulets are also available in the countries of Croatia, Greece, Italy and more. If your heart is set on a Turkish private yacht charter, one of the best places with the largest selection to start looking would be Turkey.