Not necessarily. A new, free iPhone app called Flight Tonight identifies all plane flights leaving within 24 hours from your home city, and shows you which airlines are willing to sell the unfilled seats at significant discounts. The sorts all flights by cheapest price. A small number of those flights will be cheaper or the same price as those booked 30 to 50 days in advance.
The spontaneous traveler can then turn to Hotel Tonight or Hotel Quickly, which shows rooms available at a discount for the same night. Recently, Groupon also launched Getaway Tonight, which shows same-day hotel deals in the U.S. The services are ideal for people who want to travel, who have very flexible schedules, and can pack and get ready for a travel adventure within 24 hours.