Whether you have a limited budget or simply want to get the best deal on a flight, traveling on cheap airlines can save you a bundle on airfares that you can apply to the rest of your vacation. Over the past few years, cheap airlines selling cheap tickets for cheap flights have proliferated -- and that's to your benefit. More often than not, there's negligible difference between a coach seat on a cheap airline and one on the Big Six (American, United, Delta, Northwest, Continental, and US Airways) airlines. In some cases, flying a cheap airline -- at least one with leather seats, free personal satellite TV, and other perks -- is superior to what huge airline corporations offer. When searching for dirt cheap airfares, check the Web sites of low-priced airlines. Some, like Southwest, only sell tickets on their own site. Others offer the best deals to their own customers. And if you buy directly from a cheap airline site, you'll avoid paying the small extra transaction fee sites such as Orbitz charge. Top Cheap Airlines to US Cities JetBlue. When JetBlue took to the skies in 2000, no one expected the airline, with its cheap fares between New York and Florida, to make much of an impact. After flyers experienced JetBlue's easy online ticket-buying technology, Airbus A320s, egalitarian single-class system, leather seats, free satellite TV in every seatback, pleasant flight attendants, and cheap ticket prices, they started switching allegiance over to the airline. JetBlue has piled up awards, including Best US Airline, Best Domestic Airline, Best Budget Airline, and Best Value for Cost from a slew of trustworthy sources. With more and more converts, this cheap but hip airline continues to grow. As of March 2006, JetBlue flies to 35 cities, including Las Vegas, West Palm Beach, Nassau in the Bahamas, and San Juan, Puerto Rico. Southwest. Deep discounts on advance purchases are typical, which is helpful to those planning a long-distance wedding that requires many guests to come from other parts of the country. When the airline has one of its frequent fare sales, the normally cheap prices drop even more. Southwest flies to 63 cities in 31 states. New Southwest planes offer leather seats. However, seat numbers are not assigned by the airline. At check-in you get an un-numbered boarding pass and are welcome to take any free seat. Spirit Air. Spirit Air flies to 29 destinations. What's different about Spirit Air is that it has two in-cabin classes -- and it's very cheap to upgrade to Spirit Plus, which offers leather seats that are somewhat roomier than coach, with more leg room, free drinks, and an odd, salty snack (who voted on feeding passengers beef jerky and cheese sauce?). Still, even cheap skates and couples on a tight budget like to enjoy the luxury of traveling in first class once in a while. Spirit's inexpensive upgrades ($30-50) are sold online and at the gate when available. Delta's Song and United's Ted are designed as cheap but fun spin-offs of their parent airlines. AirTran Airways. It flies to 54 destinations and has Hartsfield-Jackson Atlanta International Airport as its hub. Its new Boeing 737-700s feature XM Satellite Radio with more than 100 digital channels. Frontier Airlines . It has Denver as its hub and flies to 48 destinations in 29 state plus five cities in Mexico. In-cabin satellite TV carries 25 channels.