High-tech consultant Lindsay Wallroth spends 12 nights a month in a hotel room. When she stayed at the Sheraton in Carlsbad, Calif., she often found a $10-per-night "resort fee" tacked on to her bill. "Hotels charge you a resort fee because they have a swimming pool," says Bob Jones, travel expert with BookingWiz.com.

Wallroth now anticipates the fee and contacts the front desk before she gets her bill. Hotel personnel are always quick to remove the charge, and Wallroth estimates she saves $1,440 a year.

Other hotel fees to watch out for: charges for telephone and Internet access, maid gratuity, mini bar, room service and energy usage. Jones's rule of thumb: "Always challenge a fee, especially if you don't recognize what it is." To avoid charges from the get-go, call the hotel directly when you're booking (not the toll-free number) and speak to the manager, who's more likely to have negotiating power.

Fees can start piling up long before you reach your destination. Many online travel agencies, including Orbitz.com and CheapOair.com, charge $5 to $35 extra for booking airfare. Avoid that charge by going straight to the airline's Web site. Or use Kayak.com, Farecast.com or AirfareWatchdog.com to find the cheapest fare; all of them will redirect you to the airline when it's time to buy.

And stick with purchasing an e-ticket. Buying a ticket by phone or in person or requesting a paper ticket will cost more. Delta, for example, recently added a $25 "direct ticketing charge" when frequent fliers call in or show up at a ticketing office to book a flight using Delta SkyMiles.

The extra charge for checking your bag is gaining favor with airlines faster than you can say "Seriously?" United initiated the trend by charging $25 for a second checked bag. Now United and American are charging $15 for checking your first bag.

The Delta-Northwest merger will create a crazy quilt of extra fees. Delta recently upped its fee for overweight bags and now charges $80 for a suitcase that weighs 51 to 70 pounds. The new policies are expected to rake in $100 million a year.

To avoid paying up, be aware of each airline's baggage policies (see kiplinger.com/links/baggagefees). OneBag.com offers tips on packing light.

Ensuring your comfort in the air will also cost extra at some airlines. JetBlue touts its Even More Legroom seats, with an added 4 inches of space. But getting one will cost you $10 to $20, depending on the length of the flight. AirTran charges travelers with discount coach tickets $6 just to choose their seats, plus another $20 to sit in an exit row. Both airlines give you fair warning, so you can avoid these charges by accepting the seat assignment they hand out.

Stacy Rapacon is a reporter at Kiplinger's Personal Finance magazine. Send your questions and comments to [email protected]