It happened to me: A few days after I booked my honeymoon with GoToday.com, I got a call informing me that the Thailand trip we locked down for $1,200 each was a no-go. GoToday couldn’t get the rates the site bragged about, so its solution was to stick us with 20 hours in layovers, plus charge us an additional $800—and the site’s operators “don’t work weekends” so I got the news on Tuesday night after booking on Friday. And they did all of this with confidence, citing that the agreement I “clicked” on was merely a price “quote.” Since GoToday turned out to be two women in Washington state working a Monday through Friday gig manually securing travel plans, I thought I’d better explore other options. You know, the kind of instant, book-it-now travel deals supposedly available on the Internet. I searched for round-trip airfare from Chicago to Bangkok for November on six sites (with departures all within an hour of each other). Here’s what I found:

Farecompare.com
Airfare: $1,374
Site specifics Farecompare is similar to sites like Farecast.com in that you are able to book travel for up to a year in the future (the more popular Farecast only covers domestic travel). The lowest price for November was $1,141, but after selecting this price and getting to the results page, it turned out that fare was “Cheapest Advertised” and the actual “Cheapest Available Today” was $1,374. Misleading, to say the least.
Bottom line Use it, but with caution. Be aware that the price might jump up at the last minute.

Expedia.com
Airfare: $1,234
Site specifics One of the most popular (and long-running) travel sites is also still ridiculously behind with options such as flexible travel abroad. For any travel outside of the U.S., specific dates have to be searched, making it a time-consuming task to find the cheapest combination of departure and return trips. I found the lowest price when I used a Monday for both legs of the trip.
Bottom line Skip it. The outdated functionality makes it a waste of time.

Vayama.com
Airfare: $1,227
Site specifics This simple site looks good and has an interactive (but basically unnecessary) rollover map to select destinations, yet it doesn’t offer much in the way of flexible travel plans. The search for the same Monday-Monday trip I tried with the other sites resulted in the $1,227 price, but when I searched the “deals” page with the very basic request of “Asia” and “November,” I got zero results.
Bottom line: Use it, but only if you have specific dates in mind.

Kayak.com
Airfare: $1,139
Site specifics A no-frills site, Kayak powers a search engine that culls rates from various airlines (and sites like Travelocity.com) then directs you to those sites once you select an itinerary. The price Kayak touted was actually the total price (including taxes) I ended up with once on Delta’s site. Kayak also has a couple of useful features: fare alerts can be e-mailed daily or weekly; it allows you to search within a seven-day range of both departure and return trips. And charts show the rise and fall of prices for your trip over the last 90 days, plus the cheapest departure date within an entire month.
Bottom line Use it. Signing up for the fare alert e-mails alone is worth a visit.

Zuji.com
Airfare: $1,324
Site specifics Travelocity is behind this site, which specializes in trips to Asia and the South Pacific. The most frustrating part of using Zuji is that it returns results that look pretty good, but then after you “Check Seats” (in other words, actually secure the fare), it comes back with “there are no remaining valid departure dates/flights for this fare.” I got this response after trying to select the six lowest fares, so it makes me wonder why Zuji even bothers returning those results if they don’t actually exist.
Bottom line Skip it. Why get your hopes up for no reason?

UltimateFares.com
Airfare: $1,338
Site specifics For some reason this site only lets you search flex dates that are one day before or after a specific date, and the only options it offers are Saturdays and Sundays for both departures and arrivals. Also, this site is like the biggest tease you ever knew: After getting me revved up with an amazing result of $915 (for a Friday departure and a Sunday return? No way!), it delivered the blow on the booking page that the price doesn’t include $423 in taxes.
Bottom line Skip it. Avoid the sticker shock and opt for a site that includes the total cost from the get-go.