The hop on and off bus tour is the thing to do in any city. You have time to explore at your leisure and take your time with your own interests. The Guinness factory is a must see! If you check the Internet or coupon books around town, you liable to get discounts. The view from the 8th floor is spectacular!!
The people are incredibly friendly. If you can, try the Peppermint Nobs, a local candy made there in St. John's. The pubs are fun with alot of Irish influence which was surprising. The town looks alot like San Francisco with the Victorian buildings.
We went to Greenock, not Edinburgh, but that wasn't listed as a port. It was by far my favorite! The people were incredibly friendly and went out of their way to make you feel welcomed. We went on a tour with the local historical society and I'm glad we did. I would have wished to see Glasgow or Edinburgh but we'll save that for another trip.