"How have you all fared with spousal hires specifically in the US and Canada?"
I fared rather dismally: my (now ex-) wife was in medical profession and I was in mathematics. I had to change the location twice: first time when she finally got a long-term job and second when she lost it in one place and found it in another state. Once I was even seduced by my friend to accept an invitation to be a speaker at the ICM: he claimed that "if I agree, the university would certainly assist me with finding a job for her in the area" (that was when she was looking for a new job after she was told that her contract wouldn't be extended), but nothing of the kind really happened though I honestly went there.
I should say that all places I worked at were very accommodating as far as my own needs were concerned and allowed me long absences and such when we were living in different states with a small daughter (the longest commute was from Michigan to Vermont: an 11 hour drive through Canada one way) and I'm really grateful for that, but as far as finding a job for a spouse, they either could not do anything or weren't willing to and I'm not guessing which one was the case.
A former postdoc of mine was a bit luckier: they hired his wife to one place and himself to another 4 hours (by car) away. They were able to reunite 2 or 3 years later. But they were both mathematicians, so everything could be decided within a single department, which usually makes negotiations much easier.
As far as I see it, formal marriage is not really required in most places in the US, but being in different fields can subject you to all uncertainties of the political relations between different departments (from my perspective biology and medicine are, of course, closer than mathematics and medicine, but they are still not exactly the same thing). I wish you all the luck, but be ready for a bumpy ride at least in the beginning and try to be flexible and consider sacrificing some of your ambitions if you value your relationship.
Everyone's experience is different of course, but you asked and here are my 2 cents :-)