It wasn't long after the merger was announced that DL metal stopped flying to YOW in favor of NW through DTW. For a trip this summer I was able to use BUF on DL and get if for $160 where YOW and YYZ on DL was ~$650 and ~$800. We do this trip every summer and in the past the difference was not nearly so great. Not sure why the significant price jumps from years past.

I am looking at a YVR trip in August and SEA + rental car is starting to look attractive.