Down the street from Gucci and Cartier, the St. Regis opens among Istanbul’s most high-end shops.

Why Go: St. Regis loyalists will now find what they are looking for in Istanbul. The 118-room hotel that opens in April has a way, like many of its sibling properties, of creating an oasis of international standards in the midst of a big, overwhelming city. Floor-to-ceiling windows quietly frame Istanbul’s landmarks and the distant Bosporus. Guests look down from amid acres of marble that line the public spaces…