However if you say that Canada is part of the VWP and then someone goes to look up what the time contraints are on actual VWP visitors, they'll think they only have 90 days and then come back here even more confused.

See
Voyage.gc.ca for specific info.
QUOTE
Canadian Retirees/Snowbirds
A maximum admission period of six months is expected to be the norm for Canadian retirees seeking to winter in warmer climates. Those who wish to stay longer may apply for an extension with the nearest office of the U.S. Citizenship and Immigration Service once they are in the United States, but before their authorized stay expires. They may be asked to demonstrate that they are only remaining temporarily in the U.S
If you're planning to stay in the US to wait out the visa process, you'd fall into this category of Snowbirds.
As for myself, I stayed in the US for 5 months when we were waiting on our petitions to be approved. When I entered the US (Nov. 2003) I had no job and no ties to Canada other than a couple bank accounts. I had a 3 month return ticket, which I changed about a week after I arrived. I told the border guard that my husband and I were waiting on immigration paperwork, and that I'd just been laid off from my job of 13 years and needed an extended holiday. He asked me if I had any chocolate for him, and sent me on my way (he was suffering a sugar high from Halloween). I lucked out that time, considering I had abslutely no ties to Canada, but he was in a good mood I s'pose.
It was only questioned at my interview when she asked how it was possible I could live without a job for so long. I'd been given a fairly good severance package when I got laid off, so I had plenty of money to support myself during that time.
If you drop everything and quit your job etc in order to have an extended stay in the US, they will ask you if you have money to fund your stay. Saying that you'll be staying with your spouse will not necessarily be sufficient, they'll want to know if you have cash flow of your own. If you don't, they'll suspect that you'll be working illegally, and will likely deny your entry.