The advice given regarding your best route is pretty much spot on. In the end, it's whatever it is that works best for meeting you and your partner's wishes and needs. After assessing those requirements, you can build your "case" from there.
As far as getting through CBSA, of course don't assume you'll be allowed into the country, but also don't worry too much about it even if you aren't working anymore. They might not even ask. Having crossed many times as a US citizen -- both via air and land -- pretty much all of my experiences crossing have been uneventful. One time when my spouse and I were crossing by car, we were both given the runaround, but that was because we got the wrong officer (our line was very slow, and it was because the officer was hassling pretty much everyone... all other lines were going much quicker). Despite the runaround, we didn't even have to go to second inspection. The first time I came to visit my wife (then girlfriend), the officer at the airport asked what I did for a living and for proof of a return flight (which I had). I didn't have my itinerary printed out, so I had to fumble through my phone and email. The officer took my phone and clearly started thumbing through my email, which proved I had a return flight and was a grad student (school messages galore). Then she let me through and resumed berating Asian tourists. Those were my worst experiences with CBSA. For Americans they usually ask very basic questions and don't bother for proof. Hell, there were two times where I was basically waived through without a word once they saw my US passport. So, basically, it all depends on the CBSA person you get, but know that as a US citizen, you're probably not going to get the runaround. Answer their questions succinctly and try to not give them anything to latch on to and question.