Well, I think we could annex Alberta, Newfoundland and Nova Scotia as well. British Columbia, Ontario and Quebec are lost causes. PEI I'm not sure.
If we did, we'd have to say goodbye to the Republican Party. Practically the entire economies of those three provinces consist of wealth transfers from provinces further to the west in the form of welfare and the like. (How did they get that way? Decades of working for nationalized "Crown corporations" that were so corrupt and/or Soviet in their busines practices that the companies all collapsed. The citizens of those "states" would all vote about 90% RAT as American citizens; that's six guaranteed RAT senator until the end of time, lord knows how many electoral votes ... basically the Democratic Party would end up with full control of the presidency and Congress for the rest of time.
Alberta is definitely one of the more conservative provinces. But despite who may be currently in power, the other prarie provinces are also fairly conservative -- Manitoba and Saskatchewan. BC I'm unsure about. They've got a lot of immigrants there, but I think that many of the more rural ridings (districts) outside of Vancouver elect more conservative parliamentarians.
Ontario's politics are like NY's or Massachusetts. The folks there are liberal, but vote for the occasional non-leftists to run their own government like NY and MA both have Republican governors.
Quebec is a completely lost cause. No way we'd ever want that.
The maritimes are all very left wing. They elect the crazies. They don't have much to offer economically.
So, in the end, I'd probably be satisfied taking BC, AB, SK and MB. That would also maintain geographical integrity. Ontario and the Maritimes could keep the Canada moniker, the anthem and the maple leaf flag. Quebec could become its own crazy country. And that little enclave that is still owned by France would stay French...