Originally Posted by
lax2010
One usually uses the ITA tool to find the routing before heading over to third party website like orbitz.com or expedia.com to book it usually with multi-city mode.
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.