Hi Flahouses, welcome to Cruise-Chat. I, personally, love Costa. It's not like Carnival in the least. It is an Italian line, there are many more children on board. They have great food, the ships are beautiful and very well maintained, the crew is fantastic. You'll love toga night. I hope they're still doing the tours of the countries. They give you a passport and you go to various shops where they have food/wine from various countries to have your passport stamped. The entertainment is very good. What most people don't like is that all the announcements are in 5 languages. English is not the main language on board, but you can find someone who speaks English. They all try their best, but sometimes things get lost in translation which aggrevates some. I find that a please and a smile go a long, long way. They have activities for children on board, and all the children seem to have fun.
We did our snorkeling in Grand Turk through the ship. We had 2 great snorkels, one stop was for the coral and one stop was for the sea life. The water was crystal clear and the coral formations were great. This was before the hurricane, so I don't know how well the coral survived. There is a nice beach area with shopping right at the dock. I haven't done any snorkeling in San Juan. I have heard the waters are full of sharks and it seems to always be pretty rough when we've been there. If St. Thomas is one of your stops, take the ferry over to St. Johns and the cab up to Trunk Bay. There is a self-guided snorkel trail about 50 yards from the beach. The water is absolutely beautiful and the snorkeling is very good. Hope this helps some and sure hope you enjoy Costa. They will play Dean Martin's "That's Amore" when you're leaving port. If you go with an open mind, don't compare it to Carnival, y'all will have a fantastic time!
Check out our Caribbean Port Chat section. It's a little further down the main page. You can use your "Find" feature in the upper left hand corner and type in your ports. It will pull up all the posts made. You might find something that interests you. Best wishes and have a marvelous cruise!