Don't miss the Royal Mile! Tour the castle, visit the woolen mill, soak in the awe of the Cathedral, Have lunch at the Whiskey Museum Restaurant, and while you're at it visit the Writers Museum and the Scottish National Museum. After that walk down the hill to Grassmarket Street and check out the second-hand stores. (You might find an antique kilt) The Brittania is moored close to your ship, also worth a look. Edinburgh is a city that can't be seen in just a couple of days, but you'll see enough to experience the flavor and I guarantee you'll want to go back!