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It's an assumption you've heard before: Travel agents are a dying breed. Many people presume that the rise of do-it-yourself booking engines like Travelocity.com and Expedia.com all but wiped out travel agencies -- Yahoo recently declared a career as a travel agent a "dead-end job." But that's not necessarily the case. Travel agents still have their place: In fact, members the American Society of Travel Agents book more than 144 million vacations a year, and ASTA reported more than $17 billion in revenue for 2012.

In an attempt to change consumers' views, John Pittman, a vice president at ASTA, said the society prefers to use the term "travel professional." This term describes the profession more broadly as today's booking agents do more than act as the go-between for travelers, airlines and hotels. Travel professionals now work across multiple platforms (even using DIY sites) to help clients book a wide variety of vacations. "The truth is, travel agents have adapted to the changing environment, and they are relevant and they are meeting a consumer need," Pittman said.

[See: Why it Pays to Book With a Travel Agent ]

Jeff Klee, the CEO of DIY-booking website CheapAir.com seems to agree: In June the site announced it would begin offering every customer who purchases a plane ticket access to a CheapAir.com travel adviser who can be reached directly by email or phone. The adviser can help you make modifications to your booking, deal with trip delays or cancellations, or organize additional elements for your booking, like car or hotel reservations.

Even still, there are certain instances where it's more beneficial to book with a traditional travel agency rather than to attempt to organize a trip on your own. Pittman cites five examples as optimal opportunities to use a travel agent:

International travel

In addition to providing some destination-specific advice, travel professionals can negotiate international hotel and flight packages for you to help trim the costs on a trip overseas. Pittman also stressed that things can get tricky when traveling abroad, especially if you're visiting a nation with complicated visa or passport requirements. Not only can you get a better value when you use a travel agent, but you also have the peace of mind that you won't get stranded in a foreign country.

Honeymoon travel

You've got enough on your plate when it comes to organizing your wedding -- let someone else plan the honeymoon. Not only can a travel agent get you discounted rates, but they can use their established relationships to provide you with special honeymoon perks like room upgrades, welcome amenities and candlelit dinners.

Large group and corporate travel

Thanks to their industry contacts, travel professionals can help you negotiate large-group discounts and organize all of your itinerary details so your family reunion or your corporate retreat goes off without a hitch.

Cruise travel

Planning a cruise may sound easy, but you have to consider a lot of variables. What itinerary is right for you? Will you be spending an extra night in the departure or arrival port? Do you need to book a hotel room or car rental? What shore excursions do you want to sign up for? A travel professional can help you sort out all of the intricacies of your cruise and use their connections to secure unadvertised deals. If you're hoping to use an agent that deals exclusively with cruise travel, you can search for one through the Cruise Lines International Association CLIA offers an Accredited Cruise Certification for agents, which means travel professionals with this credential have gone through extensive training in order to better match travelers with the right cruise itineraries.

Theme park travel

Theme park vacations can get expensive quickly, especially when you factor in daily park expenses like tickets and food. Though places like Disney World routinely advertise package discounts to entice vacationers, a travel professional can help you distinguish between a good deal and a deal that's too good to be true. He or she can also find you those under-the-radar discounts, such as special family or group rates.

[See: How to Save Money When Booking Travel Online ]

If you decide that your upcoming vacation requires an expert planner, choosing the right professional is key. Pittman offered five tips to help you narrow down your choices.

Look for an accredited agent

ASTA is the only professional association that represents travel agents, and it's the only organization that has its own code of ethics (meaning ASTA members are required to respond to customer complaints). Many travel agencies include the ASTA badge on their websites, but you can also search for an ASTA-accredited professional on the association's consumer website, TravelSense.org .

Ask your friends

As with any investment, it's helpful to get advice from your family and friends. Ask for agent recommendations from people you know have used travel professionals in the past. Pittman reiterates that the best travel professionals strive to create long-lasting relationships with clients that go beyond a single booking experience.

Check credentials

If you can't tap friends or family for recommendations, rely on the industry's accreditation system to guide you to the right agent. Some travel professionals are Certified Travel Counselors, which they've earned through The Travel Institute (the certification body for the travel professional industry). Agents can even become "destination specialists" through the program, meaning they become experts in a given region. Some of these certifications can be attained through remote course study, while others earn the title through extensive first-hand travel experience.

Ask about fees upfront

After your travel professional supplies you with a vacation package estimate, make sure to ask if there are any additional fees and if the cost of an agent's service is included in the quoted vacation price. If the sight of "service fees" has you rethinking the use of an agent, keep in mind that an agent's on-ground contacts and affiliations can likely score you more free extras and discounts that you wouldn't necessarily be eligible for if you made the travel plans yourself.

Check the agency's record

If you decide to book through an ASTA-certified agency, you can be sure that the agency adheres to the association's code of business ethics. If you go with an agent that isn't connected to the ASTA, you can still check up on its business practices through the Better Business Bureau to see if any complaints have been filed against the agency or individual you're considering.

[See: How to Solve Tricky Airline Customer Service Situations ]

-- Ann Rivall