For Canadians if you want a package (room + air) probably Expedia offers the best overall prices.
But avoid any flights that have USA based connection cities !!!! The last thing you want to do is having to clear USA TSA, customs and immigration in the USA twice and the delays associated with it.
If you want to do it separately then from an air perspective best prices can be usually found on Westjet when they have a sale on(usually frequently) or Interjet if you are close to one of their hub cities - Montreal (YUL), Toronto (YYZ), Vancouver (YVR)
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