Trips that are a long way off

Planning a trip a 6 months or more in advance leaves plenty of time for a problem to crop up.

Expensive trips

Any time you have more at risk than you can comfortably lose, you need to consider insurance. To do the math, determine what portion of your trip is nonrefundable should you cancel beforehand, and how much you'd lose if you needed to return home midtrip.

Complex plans

Ask yourself: Could one problem derail your entire trip? For example, a significant flight delay could mean missing your cruise ship departure or cutting a city out of your two-week whirlwind tour of Europe.

Cruises

Because the cruise lines offer travel insurance, and because the travel agents offer it, the cruise lines have a no-excuses policy. If you don't have insurance, you're out of luck.

Package deals

Restrictions often stipulate that a change to any portion of the package will result in all rates reverting to the regular price.

Last-minute plans

Making plans a day or two before your trip doesn't leave much chance for the unexpected to occur. You know you're in reasonably good health, for example, or whether a hurricane is bearing down on your destination.

Domestic trips

The fee to change your flight is small, usually $100 or so. And most U.S. hotels allow penalty-free cancellations up to the day before you check in.

Short vacations

Should you need to cancel, the nonrefundable portion of your trip is likely to be small. It's also less likely you'll need to come home early.