Acknowledging we're not "cruise people" and have no real desire to be on a huge ship after spending the afternoon in SanTorini with the crowds getting to the dock, so I have no comparison to the big ships, but we have taken Viking and they were better in every category in comparison; communication, food, tours, structure. WindStar seems to be lacking in communication in a lot of areas. We got mixed messages on what to wear for dinner even though i called the offices on the West Coast. We were surprised to see that even a glass of wine with dinner was extra and swiftly felt that everything was not only expensive but Nickle and Dime'd doesn't begin to describe it. We had time to order private tours in a couple places since we were in Istanbul early, for less than the group tour that Windstar offered. I have to say that the Windstar tour of Delos was exceptional. That guide was excellent, but again, if you didn't keep up, you missed some of the dialoge.
On San Torini for instance they dropped us off at one end of the wharf and picked up at the far end behind a number of boats that hid the tent. It took 15 minutes to even find it.
IStanbul was similar event.