I have been there. St Croix is the largest island and is also the most "business" oriented. The seat of the government is there (I think), as well as the HOVENSA refinery, and an Alcoa facility. Despite some of the industrialization, it's still a very beautiful island. The industry is located well away from the touristy spots and nice beaches. You probably won't even see the refinery.
That said, St Croix has the least amount of actual tourists. The last time I was there (about 7 years ago), Fredericksted was almost a dead town due to a hurricane, and Christiansted was growing. The major cruise ships stopped making call at Fredericksted (the deep water pier) and smaller boats began to arrive at Christiansted.
Just off of St Croix is Buck Island. It's a natural sanctuary and there is NO development. It has one of the most beautiful beaches I have ever seen. Matter of fact, it's been used in several advertisements. Do you remember the Pepsi commercial where the little boy sucks himself into a bottle through a straw? That was shot on Buck Island. There is no camping there or overnight stays. You can take tours by boat, but everyone has to be off the island after dark. There is also an underwater snorkel trail.
St Thomas is the most touristy island. It's a major port of call and has all the t-shirt shops and souvenir crap. I don't care for it.
St John is mostly national park and has the least amount of development overall. There are a couple of hotels on the island that might be able to set up a wedding package of some sort for you. Getting there is a bit of challenge. You have to fly into either St Croix or St Thomas, then seaplane it or ferry over to St John.
Also, the cars are all left hand drive like here, but the cars all drive on the left hand side of the road. It's very daunting, and making right turns isn't for the faint of heart. The Cruzan people are friendly to a fault. Everyone is greeted with a "good morning", "good day", or "good evening". Everyone! The same is expected when you leave somewhere. They're also very, very religious so the beaches have no nudity or hanky-panky, etc... I saw one woman go topless at a beach there and she was quickly advised to cover up. This might be a good thing if you've got kids in tow, etc...
There is some casino activity which is relatively recent (within the last 8 or 9 years). I don't know how many are there now, but I was at the first one built on St Croix for a Bar Mitzvah. It's called the Divi Casino Resort. I don't gamble, so I can't comment on how good that part is. The hotel was beautiful, but it's on the east side of the island which Atlantic, not Caribbean. The water looked quite rough compared the north and west side beaches.
Overall, I wouldn't recommend USVI. It's nice there, but everything is EXTREMELY EXPENSIVE!!! For instance, there is little to no natural fresh water. Most everything is from desalinization plants. Almost everything is shipped in from milk, to eggs, to bacon. A reasonable dinner for two can go well past $100.
There are other, better destinations IMO. Check out Costa Rica. It's cheaper there and far more interesting. You'll need some passable Spanish though. It's not like Mexico where everyone seems to speak English. The Ticos like Americans and Canadians, but they don't feel the need to learn English just to keep the touristas happy. I kind of like that.