The Hotel Les Ottomans in Istanbul is pretty underrepresented here, although it ought to appeal to the Four Seasons Fans, in terms of decoration, service and price levels. Costs at least twice as much as the FS. I only did a site inspection.

Bebek Hotel is a connoisseur alternative http://www.bebekhotel.com.tr/history.asp, especially if you are doing business on the European side, want to be among local high society and not visit the tourist attractions in Old Istanbul.