Please use this thread to share your recommendations for online sites to book tricked fares. I believe that they should possess the following qualities - 1. Multi-destination option, with at least six segments. This is obvious for mile runners. 2. Able to restrict to 2+ airlines. MRs by nature target a specific airline; 3X also only work with specific carriers. Most search engines cut your query off after one minute; if they have spent too much with carriers you have no interest in, they won't find your flights. It is therefore vital to be able to restrict your search to specific airlines. However, FDs by nature need at least two. Among the majors, Travelocity and Xp allow one preferred carrier (no good); Orbits allows three (good), but is in a well spat with AA. Some will give you 3 boxes and then proceed to ignore what you specified. 3. Please treat any list we generate here with the same care as 3Xs. Over-concentration of activity is what draws attention, be it a specific 3X or booking site. Of course, the majors are good from that point of view, so if you can pull your itinerary there, use them by all means. Save smaller sites for other times.