A columnist in the NY Times today wrote about the experience of a couple who thought they were buying insurance for a cruise which would refund their money in case of an emergency that prevented them from traveling. They spent over $9000 for the cruise, and $978 for the "protection" plan.
Unfortunately, they neglected to read the very fine print which said that the promised refund in the protection plan would be in the form of a travel voucher. The husband had a heart attack before the scheduled cruise and later died. It was only because the NY Times got involved (and the daughter is a lawyer) that the family was apparently able to get a cash refund, although they couldn't divulge the actual details.
One conclusion I drew from this story (although it's not made explicit in the article) is that it is probably a better idea to buy trip insurance through a separate insurance company, not from the company that is selling you a cruise or some other excursion. The insurance company is not likely to have a financial interest in giving you a travel voucher rather than a refund.
Also, of course, always read the fine print, but a lot of times these companies sell you the "protection" plan on the phone while you are booking the travel, and don't make it clear in any way exactly what is their definition of protection.