If you're booking a multi-city trip by air, you should really price it out as a series of one-way flights, rather than as a single ticket. As Mike Masnick discovered, the arcane airline ticketing rules require ticketing agencies to stick random, high-priced business-class tickets into multi-hop itineraries, which can double the cost of your trip. The ticketing websites -- Expedia, Travelocity, Hipmunk, Kayak, and Orbitz -- all either failed to show this information, produced suboptimal itineraries with unnecessary overnight layovers, or obscured the best flights in some other important way. Masnick got a spokesperson for Hipmunk to explain it all:
After going through all of this, I reached out to folks at Hipmunk, to see if they could explain the result. Hipmunk's Adam Goldstein kindly explained the basic situation, noting that airlines have all sorts of rules about what tickets can be combined with others. If you've never dealt with the insane details of fare classes (which go way beyond seating classes), you can spend way too much time online reading the crazy details. Given that, it seems that it is these kinds of "fare classes" that are the "culprit" -- and by "culprit" I mean the way in which the airlines force you into spending much, much, much more than you need to.
That said, Goldstein also argues that there are downsides to buying individual flights. He brings up, as we discussed above, the issue of connecting flights (and also having bags checked all the way through to destination) -- but as noted, that doesn't apply in this situation. He also points out that if you have to "change or cancel your whole trip, you have to pay separate change/cancel fees for each booking, instead of one for the whole thing." That's absolutely true, but is that "insurance" worth paying twice as much? I could rebook my entire trip with different times and dates... and basically pay the same total amount. So... that argument doesn't make much sense.
In the end, it really feels like a scammy way of making fliers pay a lot more than they need to, without them realizing it. What I do know, however, is that if you're looking for the best deals, do not assume that a multi-city search will turn up the cheapest prices -- and also recognize that the different search engines can give out extremely different answers. For example, if price was the only concern, and short flight times/non-stop flights were less important, then obviously that British Airways option at the end is by far the best price -- but it turns up on none of the other search engines. However, I'd imagine that most casual fliers have no idea, and I wonder if many people end up booking multi-city flight options, not realizing that they could save a ton by booking the exact same flights individually.