Can't believe there is any of the North American destinations mentioned without a 1-change option (i.e. same as LHR) via ORD, BOS or JFK, with the possible exception of YYT. Obviously the flight time to the US change would be 2.5-3hr hours shorter than going to LHR and tracking back.
[clickety...] Is CO still going through SNN? If so YYT can be accessed via EWR.