In the age of DIY online travel, who needs travel agents? Well, you, maybe. Here’s the scoop:

Call an Agent When …

Time is money: Let a savvy agent watch for lower fares. (The transaction fee pays for itself when the price drops $500.) And an agent can undo complicated reservations and reissue tickets and credits.

Booking complicated trips: Foreign destinations? Multiple flights and visas? Seamless transfers? Let someone else handle it.

You want perks and upgrades: Flights, hotels, car rentals — agents know the inventory, have the connections, and can get special bulk fares and deals (on say, the NY-DC shuttle).

You want the hotspot in peak season: St. Barth’s for New Year’s? Amalfi in July? Agents can call in favors to get you in — with better rates and upgrades. Michael Holtz of The Smart Flyer (the agent we have on speed-dial, 212-268-9088) gets clients into members-only clubs and restaurants because he’s in with the right concierges.

You want special treatment: The new agents (Fischer Travel Enterprises, Andrew Harper’s Q Club) are all about the personal touch and access to the people, places, and events. Lisa Lindblad(another favorite of ours) scored one art-loving client an artist’s tour of Florence’s best (and unknown) studios.

Go Solo When …

Flying point to point: LAX to ATL? A basic week at a spa? Use a one-stopper like kayak.com.

Money is an object: Many sites (Orbitz, Travelocity, American) will search for flights on days surrounding your desired dates, which can make a huge cost difference.

You’re going JetBlue or Southwest: Their fares are too low to pay an agent’s fee.

You have primo status: Platinum flyers should call the airlines directly, because they know your flight patterns and will do everything possible to keep you happy.

Bottom line: As in most things, the right relationship really is everything.