In June, Ken Kessler, 54, received an e-newsletter from VacationsToGo.com promoting deals for Alaskan cruises in various categories.

He and his wife were able to book a weeklong trip earlier this month in a balcony cabin on the fourth deck of Carnival's Spirit for $849 each. For no additional charge, the cruise line subsequently upgraded them to a cabin with a larger balcony three decks higher.

The same accommodations would've cost nearly twice that much had they booked the trip more than 90 days before departure and had they traveled in July and August, the peak of the summer vacation season.

“;The best shopper is a knowledgeable shopper,”; said Kessler, general manager of Atlantis Navatek Cruises. “;After you've done your homework, you'll know a good deal when you see one. I think going to Alaska in late summer, after most of the tourists have gone home, is the reason we got such a good fare. That's why I prefer traveling after Labor Day, if it's possible.”;

Like Kessler, more and more travelers are finding they can enjoy substantial savings if they have the time and patience to do the research themselves. Dozens of online Web sites - among them household names such as Orbitz.com, Travelocity.com, Expedia.com and Priceline.com - promise generous discounts on airfare, hotel rooms, car rentals, cruises, activities and more.

Carol Goto, 64, is a fan of Yapta.com, which tracks fares for major carriers such as United, American, Delta, Northwest and Continental that have a “;Guaranteed Airfare Policy,”; meaning they will provide a credit or voucher if a purchased ticket becomes available at a lower price.

Last summer, Goto, an administrative assistant at Macy's, received a $327.98 voucher good for future travel on United by paying attention to Yapta alerts. “;I originally paid $1,011 for a round-trip ticket to Seattle,”; Goto recalled. “;I input that information on Yapta, and it sent me an e-mail every time the price of my flight went up or down.”;

Most airlines charge rebooking fees of $50 to $150 for domestic flights and $200 to $250 for international flights, so in order to be eligible for a credit or voucher, the savings must exceed this fee.

“;When the savings reach a certain amount, Yapta recommends that you act,”; Goto said. “;I got my voucher from United on my own, but it was easy because Yapta told me exactly what to do and say.”; According to Yapta's Web site, the process can be completed in eight to 12 minutes.

A few things to keep in mind: If you take advantage of the lower price, you might be downgrading the class of your ticket, meaning you may forfeit perks such as waivers on baggage fees and bonus frequent-flyer miles.

Also, vouchers are typically good only once. If you have a $100 voucher and use only $80 of it, you will lose the balance. Credits awarded to your e-account, however, usually retain full value. Given the same example, you would be able to use the remaining $20 for another flight.

It's important that you contact the airline as soon as the fare goes down, because it could conceivably go up within a day, perhaps even within an hour. Airlines will issue a credit or voucher only if you contact them while the lower fare is available.

Travel guru John DiScala calls Manhattan Beach, Calif., home even though he figures he's on the road 265 days out of the year. He launched JohnnyJet.com in 1999 “;to point travelers to everything the Internet has to offer,”; and it's been growing exponentially ever since. With more than 5,000 travel-related links, the site is one of the most comprehensive Web-based directories of its kind.

Readers are invited to submit suggestions on how to travel economically, comfortably, efficiently and in style. “;The best way for consumers to find the best deals is to shop around,”; DiScala said. “;There's not one Web site out there that has the best price every time. That's why I created JohnnyJet.com - to show travelers all the available options.”;

Among DiScala's top tips: Be thorough in your research; book packages, which usually wind up being cheaper than paying for airfare, room and rental car separately; and be flexible with dates, times and itineraries.

In general, you'll get more attractive rates by flying Monday through Thursday and by using secondary airports. To assist with the latter, DiScala created AlternateAirports.com, which lists options for more than 100 major U.S. cities.

“;If you're willing to drive a little, you can save a lot,”; DiScala said. For example, instead of Miami, look at Fort Lauderdale, 26 miles away; instead of San Francisco, consider Oakland, 30 miles away; instead of Chicago, fly to Midway, 21 miles away.

“;Making travel arrangements online is not rocket science,”; DiScala said. “;All it takes is time and tactics.”;