You will get a lot of different opinions on cruising. As I have said in other threads, "who is the best" is very subjective and relevant to what you experience. I remember sitting at Miami airport after coming off the CCL Victory. I had a group of 30 people who enjoyed the cruise and all had a wonderful time. But yet, this lady at the airport was complaining to a stranger about how horrible the same cruise was, nothing pleased her. I think for your age bracket Carnival or Royal Caribbean would both be good choices. The private islands can be relaxing and fun. They usually have a big BBQ and activities to do.