Hello pamk14
This was actually how we did our wedding. We chose Bermuda as our port, and planned our wedding through the cruise line's wedding company. A word of advice, look into coordinator's at your port, rather than use the cruiseline's company. Their customer service isn't always up to par, and I know I'm only one bride out of thousands, but it can feel at times like they don't really care. At least that was my experience with the woman we worked with. If you want a good resource, Cruise reviews, message boards, bargains, cruise information - CruiseCritic.com has a Honeymoon & Weddings forum that you can browse through for more information. (Honeymoon & Wedding Cruises - Cruise Critic Message Boards)
We did have an amazing wedding, but this was due to an island company called The Bermuda Wedding Salon. The cruise company subcontracts out to them due to Bermuda law, and they are the reason our wedding turned out as well as it did. The woman in charge (Barbara Whitecross) is extremely professional, and gets right down to the details. She wants your wedding to turn out well, and she wants you to get what you pay for.
I have a review of my wedding here on these boards, but if you have any other questions please let me know, I'll answer them as best I can.
Good luck with your planning!