Had she merely visited Canada and returned to Thailand, I would have given her a 100 percent chance of success getting a B visa. The reason is that despite being married to a Canadian citizen and thus having strong ties to Canada, she would have returned to Thailand.
Since she has expressed immigration intent to:
* USA (K-1 visa is a dual intent)
* Another highly developed country that her spouse is citizen of (Canada)
then being a Canadian PR harms her case more than it helps to get a B visa. Owning a home in Canada marginally helps her case but over all, her ties to he USA (through you) are stronger than her ties to Canada.
Aren’t back logs for a B visa long too?
I think the path of least resistance is for her to become a Canadian citizen. No visa, no ESTA.