Most vacation destinations exhibit at least some seasonality, and many offer low off-season prices. Low seasons vary by destination: The best prices in the Caribbean are in the fourth quarter of the year. The best prices in mountain resorts are found in fall (before the skiing starts) and in spring (after skiing is over but before the summer prices peak). Low seasons in big cities are the month before and during the Christmas and New Year's holidays. Low seasons at Disney resorts are when kids are in school. If you aren't sure about seasonality, check Hotwire's TripStarter, which tracks average prices for airfare and hotels for many popular vacation destinations. Keep in mind, however, that the vacation experience is often very different in low season than in high: Scottsdale in midsummer is not as appealing as during winter-snowbird time.