Originally Posted by
jackal
I booked mine (EWR-IAH-SFO-ONT-SFO-IAH-EWR) on united.com using the multi-city function. IME, third-party sites are only necessary in the following situations:
A) Certain multi-carrier itineraries
B) When a mistake fare is actively being pulled and is no longer bookable on the airline's own site
C) In the rare case that the airline's own site won't cooperate even on a legitimate fare
But yes, the key is to tease the routing out on ITA first before then proceeding to book at a place where you can specify the specific routing.
Sometimes when you have more than 4 segments, there is no guarantee that the .bomb booking engine will quote you the same fare classes as quoted by ITA even if you use multi-city search. Other time, it may!
Most of the time, a 6 segments itineray would even show up on Expedia without even needing to do multi-city!