Ian.com is considered the leader and has hotels.com, travelnow.com and a bunch of others under the umbrella.
JP, for flights, travel insurance, car hire I'd recommend either CJ.com or tradedoubler.com both of these sites I have earnt a good amount of commission from.
CJ dont have any problems with adsense, and vice versa is also true. So nothing to worry about. But both needs to be handled in much different way to get maximum out of them.
Cheers for the heads up, was worried I would end up getting banned from adsense if using an Affiliate program
IAN.com is great because they also let you use the hotel photographs, so if you're targeting a specific area it's a great resource. They also let you use their text descriptions. I guess it makes sense, since using photos and having descriptions will increase the conversion rates. Ian
I would defenitaly vouch for WCT, www.wctravel.com Have been with them for some time, great support, better payout that ian.com, much better statistics. For hotels, last minute and vacation packages they are the best, but they still need some work done on car rentals and flights. At this time the layout etc. is not that good, but they are working on it and should have a new interface for them by the end of the year.
Remember if you go via commission junction they're eating a major share of the merchant's commission which could be going to you if you worked with the merchant direct. That's one of the reasons we avoid them at Twibo. We want the affiliates to earn the commission, not the middlemen.