Speaking as a professional, travel photography is kind of a mixed bag in terms of where the images actually come from.
First, any actual site specific images of a hotel or resort more then likely was photographed for the resort. The resort hired the photographer to create marketing images for them, and got a usage package that probably covered a fairly large amount including publication. For these assignments, the photographer was probably paid well.
Of course, in addition to photographing the resort for the resort, one might get hired by the architect or designer to do the same thing. In this instance, it is more then likely the resort would have also paid for usage of the images too, but if not, a magazine wanting to use the images would have had to pay the photographer. Here, the fee would have been relatively low, and certainly would not have covered the actual cost of the shoot, but that would have already been covered by the commissioning client. So although low, it's would have been extra gravy for a one time usage, which is not worth that much anyway.
It is very rare for a magazine today to hire a photographer directly with an appropriate budget to do any kind of resort or travel work, unless the images were in a genre that could be used extensively for a products much more accessible, like fashion. Hence Rob's suggestions. Here though, the images would have most likely been used in the fashion magazines first. If the magazine did in fact send a photographer to only shoot the resort or location, the budget would be very low (in today's market) and the photographer more then likely would be working by himself relying on natural/ambient light.
Last, there are photographers, who for one reason or another, do quite a lot of traveling independently. Being photographers, they take pictures while doing so and build up a huge library of images captured in exotic locations. Editors know this and if they need one or two random pictures of some exotic place no one has ever heard of, more then likely some photographer out there who does a lot of traveling will have already photographed it for himself. So, they will send out a mass email to a couple hundred photographers (they keep on file) asking if anyone has images fitting this criteria. When someone does have an image the editor needs, it will be treated as a stock purchase for a one time non-exclusive use.
There are actually photographers who do only travel photographer like described above and make it work full time. What they make is not great and it take a fair amount of time to make the connections and library to pull in good money, but surely an adventurous lifestyle to say the least.