We swear by our travel agent, and have used her since our first Regent cruise in 2006. One good reason among many: We had arranged through our TA to have a private tour guide in Istanbul, who would meet us at the ship. Well, no one was there when the ship docked. We called the TA's 24-hour line, and by the time we took a taxi to our hotel, a replacement had been found who gave us an excellent walking tour of the city.