Travel insurance. When you plan a trip through a travel agency or Web site, you are often asked if you want to add travel insurance that will cover your losses if something goes wrong. Travel expert Peter Greenberg says that such policies can add up to 10 percent to the cost of your trip. The most common type of travel insurance reimburses you for canceled or interrupted trips. Greenberg recommends it for expensive vacations but says the extra cost isn't worth it for short getaways. He suggests carefully comparing travel insurance policies so you know exactly what you're paying for; sometimes, exclusions include adventure travel or interruptions from acts of war.