As I stated in your other post on the subject; NEVER purchase the cruise line insurance - it's always cheaper and better policies doing it through independent companies.
Insuremytrip.com is a good tool, but two things to remember; biggest name is not necessarily best policy because it's the their customer service when a claim is filed that determines how good they are. And secondly, best price may not be the best deal.
Talk to your agent as they usually have companies they work with and feel comfortable with.
We use to sell policies from 5 different companies, but fired three of them due to bad customer service for our clients. And they were some of the biggest names in the industry! Now we sell a preferred policy written specifically for our company with wonderful customer service, which is the most important part of the whole process.
Keep in mind that you don't want to buy just any policy because you could be buying travel protection and not travel insurance, and there is a HUGE difference in the two and you definitely do not ever want to get travel protection.