Usually get good results from .bomb, it's my preferred booking tool.

Notable exception, use of priceline for deals (ORD-iad-LHR for $250 or so ai).

It's nice to be able to manage reservations/seat assignments, easy to do when flights are booked on .bomb, difficult when booked on priceline, tho perhaps that was due to a bmi codeshare designation for a UA flight...

Search sites are good for screening or for rare times when another carrier has to be part of the trip and .bomb doesn't bring up that carrier. The EQM and double RDM's are also of interest, if a UA Platinum charge card is used for payment.