A couple years ago, I had to do WAS-YYZ for work, and prices on UA/AC were ridiculous, at least on the outbound.
Found it was 25% cheaper to do: BWI-EWR-MCO-CLE-YYZ, obviously a combination of BWI-MCO + MCO-YYZ fares. Mileage increased nearly tenfold, from 250PQM to 2458PQM. Even got upgraded on EWR-MCO-CLE. Can't complain.
With close-in booking, when prices are typically inflated, it's often worth looking for an intermediate point which increases miles without increasing the price.