Hi jessmess7, welcome to Cruise-Chat. If you'll look a little further down our main page, you'll see a Caribbean Port Chat section. It's loaded with information on your ports. If you'll use the "Find" feature in the upper left hand corner and enter your ports, it will pull up all the posts made about them. There are two docks in San Juan, but I'd suggest grabbing a cab and going to Old San Juan. We haven't been to Samana, but did go to Isla Catalina and had a fantastic snorkel trip there. I'm sure there are plenty that have been to Samana.
Hope you have a fantastic cruise and once again, welcome to Cruise-Chat.