For all of the memorable and potentially life-changing experiences it can provide, travel is not cheap. The U.S. Travel Association estimates that in 2013, domestic and international travelers spent $621.4 billion on leisure vacations alone. Even if you manage to hack a deal on your flight or hotel room, there's still a surge of unforeseen expenses that can throw any budget off track. But according to Gabe Saglie, senior editor for Travelzoo, you don't have to begrudgingly give in to all the extra costs. "As consumers, it behooves us to be aware of these fees and be ready to read the fine print," he said. To help you anticipate hidden charges and plan accordingly, here are six often overlooked fees, and tips for steering clear of them.See: How to Save Money on Your Next Hotel StayAccording to the U.S. Bureau of Transportation Statistics, the top 15 major U.S. carriers raked in more than $3.35 billion in checked bag fees in 2013. Unless you're flying with an airline that offers one or two free checked bags (like JetBlue or Southwest) or you have an airline-affiliated credit card that waives the standard $25 fee, you'll need to try your hardest to fit everything you need into a carry-on. Saglie offered this advice for perpetual over packers: "Think like a business traveler. Streamline as much as possible."Avoiding these fees can be easy, but as Saglie notes, you'll need to "learn to love the middle seat." Paying extra for the coveted aisle or window, or even the more spacious economy-class seat, is a cost justification that varies widely by traveler, Saglie said. "It really depends on the flight experience you want to have," he added. According to Saglie, airlines release their unsold seats 24 hours ahead of the flight's departure; so if you do get stuck with a dreaded middle seat, see if you can switch it when checking in. Asking the gate agent about available seats is another option, though you may be less likely to score a more comfortable spot as the departure draws nearer.Change fees aren't quite as lucrative for airlines as checked bags (the industry earned $2.8 billion in 2013 for reservation changes and cancellations), but according to Saglie, this is another easily avoidable expense. Thanks to federal provisions instituted in 2012, airlines are required to allow passengers to change their reservations within 24 hours of booking if the ticket is purchased at least a week in advance of the flight's departure. If you know your travel plans may change more than 24 hours after you've booked your flight, consider purchasing a refundable ticket. Though these fares are more expensive than non-refundable tickets, the extra cash you'll pay up front may be less than what you would owe in change fees. Once again, it pays to fly with a low-cost carrier like Southwest — the airline doesn't charge for reservation changes.See: 11 Easy Ways to Slash Travel CostsDespite the fact that Wi-Fi is an increasingly free commodity (according to a 2013 HotelChatter report, 64 percent of hotels offer complimentary Wi-Fi), some stalwart brands still refuse to provide a wireless network without a fee. If you're staying at a property that doesn't offer the free service off the bat, Saglie suggests looking into joining the hotel's loyalty program. Brands like Kimpton, Omni and Fairmont offer free Internet access just for signing up. If you can't access the free service in your room, see if it's offered in the lobby. And if it's not provided for free anywhere on the property, research to see if there are any cafes or eateries nearby that offer free Wi-Fi connections. Perhaps the most maddening surcharge for the modern day traveler, resort fees are said to pay for amenities like gym access, beach chairs and even housekeeping. And they're tough to sidestep, even if you don't use some of the amenities or facilities that the resort fee claims to cover. It's estimated that in 2013, U.S. hotels brought in $2.1 billion in revenue from resort fees alone, according to research from the Preston Robert Tisch Center for Hospitality, Tourism and Sports Management at New York University. Though travelers' demands to eradicate resort fees have been heard by some properties (the Federal Trade Commission released a letter calling the fees "deceptive"), others have kept the added charges. Saglie said these expenses are often non-negotiable, but also adds that you can find deals on third-party booking sites (like Travelzoo) that waive the resort fee. Avoid an unwelcome surprise on your hotel bill by asking about the fees up front — either at the time of booking or when you check in.It's convenient to step off the plane and into your rental car, but it's also costly. Airports charge rental companies a concession fee for vehicles picked up at the airport. These fees can span from 10 to 25 percent of the overall cost. To avoid the surcharge, Saglie suggested checking for car rental locations located off airport property. Sometimes, paying for a cab fare to a different car rental location (or taking public transportation there) amounts to less than the airport fee. Though, Saglie said this is also a matter of individuals' willingness to pay for the luxury of proximity."At the end of the day, fees are part of travel," Saglie said. "It's a personal cost-benefit analysis about the convenience each particular fee can bring you — could it enhance your travel experience?"See: Deal or No Deal: Weighing the Costs and Benefits of Hotel Loyalty ProgramsAnn Rivall is a Travel Editor at U.S. News. You can follow her on Twitter, circle her on Google+ or email her at email@example.com.