We believe that comprehensive trip insurance is especially valuable if you're booking an expensive trip (particularly to an isolated region), or if you're booking far in advance. Comprehensive travel policies typically cover trip cancellation and interruption, letting you cancel or cut your trip short because of a personal emergency, illness, or, in some cases, acts of terrorism in your destination. Such policies also cover evacuation and medical care. Another type of coverage to look for is financial default—that is, when your trip is disrupted because a tour operator, airline, or cruise line goes out of business. Generally you must buy this when you book your trip, or shortly thereafter.
If you're going abroad, consider buying medical-only coverage at the very least. Neither Medicare nor some private insurers cover medical expenses anywhere outside of the United States (including time aboard a cruise ship, even if it leaves from a U.S. port). Medical-only policies typically reimburse you for medical care (excluding that related to preexisting conditions) and hospitalization abroad, and provide for evacuation. Note that you will still have to pay the bills and await reimbursement from the insurer.
Expect comprehensive travel insurance policies to cost about 4% to 7% or 8% of the total price of your trip (it's more like 8%–12% if you're over age 70). A medical-only policy may or may not be cheaper than a comprehensive policy. Always read the fine print of your policy to make sure that you are covered for the risks that are of most concern to you. Compare several policies to make sure you're getting the best price and range of coverage available.